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Werner P. Schulz
08-06-2014, 04:52 PM
Today K Knopper has puplished the new DVD version of Knoppix.
http://www.knopper.net/knoppix-mirrors/
http://torrent.unix-ag.uni-kl.de/ (http://www.knopper.net/knoppix-mirrors/)

3vi1
08-07-2014, 02:25 AM
Today K Knopper has puplished the new DVD version of Knoppix.
http://www.knopper.net/knoppix-mirrors/

I just downloaded KNOPPIX_V7.4.0DVD-2014-08-01-EN.iso via BitTorrent, fired it up in a VM, and find that the LXDE menus are all in German instead of English.

Was there some image-build mixup?

Werner P. Schulz
08-07-2014, 06:17 AM
Have a look at
https://lists.debian.org/debian-knoppix/2014/08/msg00002.html

Harry Kuhman
08-07-2014, 06:21 AM
Just found the same thing. Filename has EN at the end, but the menus are not English.

There is something that shows up on the desktop that looks like it is intended to install flash (very important for my use), but it doesn't seem to actually install flash.

With my ISP metering my downloads and threatening big fines if I exceed their capacity, even after an update is posted I'm going to wait until I see some favorable reviews before I blow another 4 gigs.

Harry Kuhman
08-07-2014, 06:32 AM
Your update wasn't there when I first looked, must have been posted while I was typing my post.

I always use the torrents, so it will be interesting to see how well the torrent client can correct this mistake. Certainly another good argument for using the torrents over the mirrors. But the way, for any of you refusing to learn to use a torrent client still and who downloaded the bad ISO from a mirror, a torrent client can still make the fix for you. Here are the steps you need:

Download and install a torrent client of your choice.

Download the torrent file and start the download in the torrent client. Give it a minute, but you don't need to download a lot.

Shut down your torrent client.

Find the download directory that was created. Find the ISO file among the set of Knoppix files. Delete it. Move in a copy of the ISO that you just downloaded from the mirror.

Restart the torrent client and let it resume the download. It should spend a few minutes checking the validity of each block of your ISO. It should find one or two bad. If all goes well it will replace just the bad blocks and then announce that the download is finished. Your new ISO file should now be right (or at least less wrong than the old one, but I'm not comfortable in saying that there will be no other bugs.)

utu
08-07-2014, 02:58 PM
FYI
Distrowatch announcement of Knoppix 7.4 DVD
http://distrowatch.com/?newsid=08557

philo
08-07-2014, 04:25 PM
Yeah but with the screnshot of version 7.2

Werner P. Schulz
08-07-2014, 05:06 PM
http://www.knopper.net/knoppix/knoppix740-en.html
with topical screenshots

Harry Kuhman
08-07-2014, 09:06 PM
I got the new improved English menu version of Knoppix 7.4 today. Actually, repaired my old ISO from yesterday with Bittorrent. Got the new torrent file, started my client. The scan of the ISO to find the bad or missing blocks took longer than actually making the repair and then start seeding. Had the fixed version in just a few minutes.

7.4 is working better on my hardware than 7.2 did. The menus are in English now (for the EN version).

Adobe Flash still requires running an install script (the install scripts now offer several additional pieces of software that they did not offer in 7.0). This was painfully slow, on my system it took about 45 minutes before I was told that Flash was installed successfully. However, it was not. Like 7.0 (which worked correctly previously but stopped working some time in July of this year), sites like Hulu tell me that I need to install Flash to view their content. As I used Knoppix mainly for web browsing, this will be a deal breaker for me.

When I saw the German menu version yesterday I thought that the install flash script had been moved to a link directly on the desktop. This turns out not to be the case, in English this turns out to be a tool to install Knoppix to a Flash drive. I have not played with this new tool yet. Likely will some time soon, but unless I hear that Adobe Flash is fixed without doing extensive Linux guru level editing, my use of Knoppix will be reduced.

Werner P. Schulz
08-08-2014, 12:00 PM
..sites like Hulu tell me that I need to install Flash to view their content. As I used Knoppix mainly for web browsing, this will be a deal breaker for me.Hello Harry,
can you tell us other websites (not restricted to USA) whith which you have problems now? After using the script which K Knopper inserted within Knoppix, I've no problems to watch Youtube - neither with Knoppix V7.2.0 nor V7.4.0.
When I saw the German menu version yesterday I thought that the install flash script had been moved to a link directly on the desktop.On the desktop of the DVD/CD version you'll find a symlink to the menu entrypoint of the flash install script. Since V7.3 (the CeBIT version) this script offers some new abilities. But it seems it's still a little buggy. For me I couldn't use the option to keep some parts of persistent memory.

Greetings Werner

oleshka
08-08-2014, 02:11 PM
Hello!
Will Knoppix 7.4 CD version available soon?
Best regards, Oleg.

Harry Kuhman
08-08-2014, 08:37 PM
....can you tell us other websites (not restricted to USA) whith which you have problems now? After using the script which K Knopper inserted within Knoppix, I've no problems to watch Youtube -...
Hi Werner,

In addition to Hulu I've been watching some USA TV networks on-line with Knoppix up through June of this year. Not all worked with Knoppix but many did (if I remember correctly ABC would not play under Knoppix even before June). I completely expect that they are blocked outside the USA. I also watched movies on Crackel.com, I don't know for sure but expect that the content providers also have them blocking outside the USA. If I come up with another Adobe Flash based site that you can get to I'll let you know, but I don't have one to offer at the moment.

Of course, the regional restrictions are not limited to US providers. I would love to be able to watch the BBC and some Canadian providers but they are similarly blocked for US viewers.

As to Youtube, I'm pretty sure that they have moved away from Flash, I think they are using HTML5 and WebM and may be using other technologies. (Here's a link to an article from 2011: http://news.slashdot.org/story/11/04/20/0428224/youtube-now-transcoding-all-new-uploads-to-webm ) As a test I just shut down Linux Mint on the laptop in question and booted my Knoppix 7.4 DVD. This is a fresh boot with no persistence. I was able to go to youtube.com and play videos without ever doing the Knoppix Adobe Flash install. So I'm not surprised that you can play Youtube videos after doing the install, but that doesn't indicate that the install worked. If you come up with another site that you think is using Adobe Flash and that I might be able to access from inside the USA, please let me know and I'll give it a try.

Werner P. Schulz
08-08-2014, 10:01 PM
As to Youtube, I'm pretty sure that they have moved away from Flash, I think they are using HTML5 and WebM and may be using other technologies.
Hello Harry,

for me I've got an error message from www.youtube.com about some needed installation when I want to see a video - either with Iceweasel or Chromium. After installation of flashplugin-nonfree both browsers can play youtube videos.

With Iceweasel (and proper settings of NoScript) I can also watch videos from abcnews.go.com and www.crackle.com. With Chromium videos from abcnews.go.com doesn't start and www.crackle.com ask for the latest Adobe tool.

Harry Kuhman
08-08-2014, 10:28 PM
On Youtube, I had only tried Chromium since I already knew that I didn't want to muck with the noscript issue in Iceweasel. Chromium played the video, confirming that Adobe Flash was not involved, so there was no reason to investigate further.

Sounds like you saw the same Crackle error that I've seen, it doesn't think we have Adobe Flash installed even though the script told me that the install went well. That is what I'm seeing on the USA exclusive sites as well, and why I'm now using Linux Mint. Mint isn't perfect, but at least I can watch the videos that I want to watch with it.

MrNovi
08-09-2014, 06:39 AM
I had no problems watching Youtube with Firefox/Iceweasel from 7.4 without installing Flash, but I did have to disable No Script to get the HTML5 to work though. You might want to look into that if you are still having problems.

My biggest problem with 7.4 is that Kdenlive won't run. I click on it and nothing happens. Tried re-installing it to no avail. Not sure what to try next.

And for the record, this is the updated ISO from what I can tell. Downloaded it at 8 PM Central Time on the 7th in the USA. The MD5 hashes checked at 394bcd5149fbbd5e86cf10c16ccaa1d3. Any ideas on what to try to get it working?

Werner P. Schulz
08-09-2014, 06:59 AM
The MD5 hashes checked at 394bcd5149fbbd5e86cf10c16ccaa1d3.And is the the check ok or not (http://knoppix.net/wiki/Cheat_Codes#Check_the_ISO)?

Jeffery Mewtamer
08-09-2014, 09:22 PM
Is there a delay on the Adriane isos? For that matter, I can't even find links to CD versions of 7.4 that boot LXDE by default.

MrNovi
08-09-2014, 09:51 PM
And is the the check ok or not (http://knoppix.net/wiki/Cheat_Codes#Check_the_ISO)?

Not quite sure what you are asking, but 394bcd5149fbbd5e86cf10c16ccaa1d3 (as listed in my OP) is the MD5 that the ISO produced and it matches the MD5 that was contained in the file that accompanied it and on the download page. I included that number as I assumed the updated ISO would have a different hash and wanted to verify that I had the latest ISO. I downloaded it again last night and the hash is the same as the previous one. I downloaded another copy today from a different source and the MD5s matched with the first two. All three of them have the same problem, but I think I figured out what the problem is.

I fired up 7.2, verified that kdenlive ran properly, right clicked the startup icon, selected properties, then checked the startup command entry, then checked it on 7.4. Found that there were quotations around the %c entry in 7.2 (which worked), but not in 7.4 (which didn't). Edited the entry for 7.4 to contain the quotes and now kdenlive starts and runs. The complete start command should be kdenlive %i -caption "%c" %u from what I can tell, or at least that is what 7.2 has and what is working for me now. Hopefully that can be changed in the next update and have the information posted in Release Notes or something so others can deal with it.

Jeffery Mewtamer
08-10-2014, 02:47 PM
Best I can tell, YouTube is the only major streaming site with enough sense and common courtesy to not require an external plugin instead of working with the tools most modern browsers have built-in. I've actually gone months without having Flash installed on account of Orca not being able to see Flash content and YouTube working a lot better in my opinion when its not trying to disobediently load the Flash player instead of the superior HTML5 player. I have no idea what Knoppix's Flash install script does, but I can share what errors I get when installing flashplugin-nonfree via Aptitude: As I understand it, flashplugin-nonfree doesn't contain the actual flash software, but instead uses wget to download flash and install the external software. With all my recent attempts, wget fails in trying to download a file from https://people.debian.org/~bartm/flashplugin-nonfree/ This an uncommon problem, but usually multiple attempts lead to a successful download and subsequent install, but wget has failed far more times than is typical. I have looked in the directory linked in iceweasel and downloaded the tar.gz I found therein, but have no idea what to do with it after decompression and extraction. To anyone more savvy at the low level provide insight as to why wget is consistently failing to download the needed files or what to do with the manually downloaded files? Also, can anyone with a working Flash Install and using Iceweasel tell me if YouTube still has that nasty habit of loading the Flash player even when you tell it to use HTML5?

otropogo
08-12-2014, 08:41 PM
Just downloaded 7.4 EN. It passed the md5 test, and the burn was verified. But running knoppix testcd, I ended up with a frozen desktop display with text in background reading:

flame name "Elektrosmog size 256x1538" etc. The swirly blue image obscured most of the text.

I rebooted, and saw no error messages, but the boot was the slowest I've seen from a DVD, it showed the root prompt after displaying "graphic environment being loaded - please wait". It took minutes to display the penguin icon, and then finally froze the system with the same Elektrosmog screen.

I had to hit reset, nothing else worked to shut down or reboot.

I tried again, setting acpi=off, but got the same result. The Intel 83865G graphics controller seems to be recognized. No idea what the problem is.

I then tried it in my UEFI laptop, and that system didn't even recognize a bootable efi device, although the efi/boot directory is on the disk, and seems to be complete. Knoppix 7.2 was able to function under the UEFI environment on the same laptop.

Finally, I tried booting the LiveDVD on my ancient Compaq Presario, and there it worked, offering the normal desktop menus with the "compiz" desktop. But operation was so glacially slow, I couldn't really test it. Still, it loaded faster than on the much newer Intel Desktop with a cpu six times faster, and much more and faster RAM.

I downloaded my copy from TUWien

Harry Kuhman
08-12-2014, 08:49 PM
Just downloaded 7.4 EN. It passed the md5 test, and the burn was verified. But running knoppix testcd, I ended up with a frozen desktop display with text in background reading:

flame name "Elektrosmog size 256x1538" etc. The swirly blue image obscured most of the text.
.....
I downloaded my copy from TUWien

I always download from the torrents, have had too many problems from the mirrors (none from the torrents and that way is faster too).

However, if the MD5 passed then I expect that your download is OK. If not, you can fix it with a torrent client without having to download everything again.

I strongly suspect that your problem could be that you did not burn at low speed. I don't like that this is important, but it really is. I've proven this time after time. Occasionally a high speed burn will boot, but it is far less reliable than a low speed burn.

Werner P. Schulz
08-12-2014, 10:30 PM
Just downloaded 7.4 EN. It passed the md5 test, and the burn was verified. But running knoppix testcd, I ended up with a frozen desktop display with text in background readingAgain your posting is dubious as all the others in the past.

otropogo
08-13-2014, 05:21 AM
I always download from the torrents, have had too many problems from the mirrors (none from the torrents and that way is faster too).

However, if the MD5 passed then I expect that your download is OK. If not, you can fix it with a torrent client without having to download everything again.

I strongly suspect that your problem could be that you did not burn at low speed. I don't like that this is important, but it really is. I've proven this time after time. Occasionally a high speed burn will boot, but it is far less reliable than a low speed burn.

I always download via ftp and have very rarely had a problem with corrupted downloads.

Your suspicion about the burn speed is unfounded too. I burned three times, once using Pburn 3.5.1 under Puppy variant lupu5.2.8-005 at the "auto" speed setting, and twice using Burniso2CD, which has generally been trouble free for me, unlike Pburn.

The last two burns were at the lowest speed offered - 4X. The first two burns failed after less than a minute, the last took 12 minutes to finish, then passed the verification test. All were burned from the same iso downloaded from TUW.

Possibly the difference was in the media. The first two burns were made with DVD+ R disks, while the third was a DVD-RW. Maybe the combination of burner, burner app, and DVD+R just didn't click. I don't burn a lot of DVDs anymore, so I don't have much to base this guess on.

The successful burn also passed the testcd test I ran from the DVD, but run on my main Desktop, that had no problems with 7.2. Its inability to boot my UEFI laptop may be due to some built in sabotage in the firmware, as it's happened to me before that the optical drive's boot capability was disabled by the system without any input from me. Unfortunately, this setting is difficult for me to find

In any case, I was able to boot Knoppix 7.4 on my slow, low-RAM 400MHz Compaq, but the demands of the desktop graphics so overwhelmed the system's resources that it took me more than six hours to finally get the usbflash install completed. A huge problem was the Compiz cube, which sat squarely on top of the usbflash installation gui, together with a system that crawled so badly I had to time my keystrokes, as they would be executed minutes after they were made.

There were program glitches in the installer too - most prominently that it failed to recognize Fat32 formatting, even after I took the flash drive to XP and reformatted it. This caused me to have to run the installer in every possible mode before the last choice - install with an overlay - finally worked.

The good news is that once I had it on usbflash, my UEFI machine recognized it and it booted, although not without a lockup at first, which forced me to power down (something that has previously spelled death for Knoppix usbflash installs of mine). Synaptic also gave me some problems the first time around. But on the second session, I was able to download and install several essential apps, including clamAV and a signature update (although the detected new gui version of ClamTK continues to evade updating).

Most importantly, though, I was able to access my 64GB SDXC card via the internal slot, something I couldn't do on this laptop with Knoppix7.2 (I could on an older Toshiba). The next hurdle will be USB3.0 performance, which is a more critical issue, since the internal slot is no speed demon.

It was also a pleasant surprise to find Darktable available via Synaptic, which now gives me a third app for editing my RAW files, the others being UFRaw and RawStudio.

I've been desperately waiting for this release because I'm going to have to give up all my old desktops for the UEFI laptop shortly, and I haven't yet found a way to make Puppy Linux run on a UEFI system. So I'm really keeping my fingers crossed that K7.4 will prove reliable.

otropogo
08-13-2014, 05:45 AM
My posts are all made in good faith. And it doesn't take a genius to see that I devote a good deal of time and effort to describe my experiences in the greatest possible detail.

Your comment above, OTOH, contributes absolutely nothing except nasty innuendo. Do you really believe that I fabricate these reports with some malicious intent towards Klaus, Knoppix, or Linux?

I've invested a great deal of time, effort, and frustration in trying to make Knoppix work for me and for others around me over the past few years. And sadly, it's never really worked reliably for me or anyone else I know. Yet I struggle on optimistically because I believe in Klaus's concept.

[snip]

MrNovi
08-15-2014, 08:37 PM
The ONLY time it's necessary (or even advantageous) to burn at the slowest speed possible is when you are using any combination of low quality media (think Memorwrecks and other cheap, no name blanks), cheap burner, or poor burning software. If you use a GOOD burner, and they can be had for $15 quite readily; good blanks like Taiyo Yuden, Falcon, Sony that are made in Japan (Sony's made elsewhere are junk), Verbatum with AZO Dye (their others are junk), and a few others, and good software like XFBurn, K3B, or IMGBurn on Windows then you will be better off burning at the disks rated speed (if the burner supports it) or no more than 1 speed slower. Forcing a 24X burner to burn 16-24X disks at 4-6x is foolish and will result in a LOWER QUALITY burn.

Honestly, this MYTH about burning at the slowest speed needs to be put to rest.

Harry Kuhman
08-15-2014, 09:34 PM
The ONLY time it's necessary (or even advantageous) to burn at the slowest speed possible is when you are using any combination of low quality media (think Memorwrecks and other cheap, no name blanks), cheap burner, or poor burning software. If you use a GOOD burner, and they can be had for $15 quite readily; good blanks like Taiyo Yuden, Falcon, Sony that are made in Japan (Sony's made elsewhere are junk), Verbatum with AZO Dye (their others are junk), and a few others, and good software like XFBurn, K3B, or IMGBurn on Windows then you will be better off burning at the disks rated speed (if the burner supports it) or no more than 1 speed slower. Forcing a 24X burner to burn 16-24X disks at 4-6x is foolish and will result in a LOWER QUALITY burn.

Honestly, this MYTH about burning at the slowest speed needs to be put to rest.

And you're dead wrong. I've proven it with Sony and Philips media and with many good name brand burners. My theory about what is happening (and I acknowledge that this is only a theory) is that when burning at high speed lots of error do occur. But since the media format wastes about 25% of actual capacity in storing error correcting codes, the errors that do occur can normally be corrected. so the drive and media manufacturers consider them acceptable. Even in normal cases I don't consider these errors acceptable. I want that excess error correcting data that is saved to be used to correct the "bit rot" that occurs over time. If most or all of it it is used to correct errors that I cause by a high speed burn, then it can't be used to correct additional errors when they do eventually occur. But in the case of Knoppix booting, something else seems to be happening. Discs made at high speed and that seem to read O.K. still fail to boot, while low speed burns boot fine. My theory is that during booting Knoppix is not able to apply the extra software error correction to make up for a bad burn. I would have expected that the reader firmware could do this, but as far as I can determine it does not. So until Linux is actually up and running and in full control of drive reading, you better have a good disc image that can be booted without depending on error correction. Burning at low speed generally acheives this, we have seem here over and over that burning at high speed can make coasters when low speed burning will not.

Werner P. Schulz
08-15-2014, 10:02 PM
Honestly, this MYTH about burning at the slowest speed needs to be put to rest.
Verifying of md5 checksum and burning a CD at slow speed are important.It's a huge difference between slow and slowest.

MrNovi
08-16-2014, 06:39 AM
And you're dead wrong. I've proven it with Sony and Philips media and with many good name brand burners. My theory about what is happening (and I acknowledge that this is only a theory) is that when burning at high speed lots of error do occur. But since the media format wastes about 25% of actual capacity in storing error correcting codes, the errors that do occur can normally be corrected. so the drive and media manufacturers consider them acceptable. Even in normal cases I don't consider these errors acceptable. I want that excess error correcting data that is saved to be used to correct the "bit rot" that occurs over time. If most or all of it it is used to correct errors that I cause by a high speed burn, then it can't be used to correct additional errors when they do eventually occur. But in the case of Knoppix booting, something else seems to be happening. Discs made at high speed and that seem to read O.K. still fail to boot, while low speed burns boot fine. My theory is that during booting Knoppix is not able to apply the extra software error correction to make up for a bad burn. I would have expected that the reader firmware could do this, but as far as I can determine it does not. So until Linux is actually up and running and in full control of drive reading, you better have a good disc image that can be booted without depending on error correction. Burning at low speed generally acheives this, we have seem here over and over that burning at high speed can make coasters when low speed burning will not.

And in my opinion you are dead wrong. I and a LOT of other users have proven it. On average I burn 50 or more DVDs and CDs a month and aside from a verified box of defective disks I've only had 2 bad burns in the past 4 years. That includes lots of music cds, dvd movies, operating install and live CDs and DVDs, and general file storage/backup.

The reason why you are wrong is that the blank disks are designed to be burned at a specific speed and burn best at that speed (plus or minus a very small amount). 16x disks will ALWAYS burn best at 16x and possibly 12x. Anything lower and it will produce MORE errors.

10 to 15 years ago it was a good idea to burn as slow as possible as there was no burn proof and computers were slow, single core systems where doing anything else tended to mess things up as it would cause the buffer to run out causing major errors/flaws in the burn. Even with Burn Proof, if that buffer ran out it would provide glitches that error correction might not be able to take care of, especially if the buffer was empty for a prolonged period. The buffer would empty when the source couldn't provide data as fast as the burner was attempting to write. This was caused by slow hard drives and/or slow processors (along with low quality blanks and burners).

Modern multi core systems and hard drives rarely have this sort of problem. As long as you don't empty the buffer you will NOT have a bad burn as long as you are using good quality disks and a good burner. If you are still using a single core system (or a single core P4 with hyperthreading) then the answer isn't to burn slower, but to burn smarter by shutting everything else down during the burn and keeping track of the buffer.

All burning slower did (does) was to attempt to cover up for system that wasn't able to keep the buffer full enough to get a proper high quality burn. While the burn would be better due to the buffer being full, it would still have more errors and be considerably inferior to what the burn would have been if it had been burned at the blank disks rated speed on a system that was properly configured to feed the buffer adequately.

What it boils down to is burning slower address the symptom, not the actual problem. If the system can feed the buffer at the disks rated speed then there is absolutely NO benefit to burning slower than the rated speed, or one notch slower. Burning a 16x disk at 4 or 8x is ridiculous and produces an inferior burn unless that is the fastest speed the burner can actually write at such as slim notebook drives. Otherwise deal with the actual issue/problem, not the symptom.

Jeffery Mewtamer
08-16-2014, 04:58 PM
On the rare occasions I buy blank CDs, I usually go for either Memorex or the cheapest thing I can find in small capacity spindle packs(I never have to buy DVD blanks as my dad records everything he watches on TV to DVD, but he usually goes for the cheapest high-capacity spindle packs he can find at local shops), generally stick to the default setting in whatever software I use, and have gotten a trivial number of coasters in the years since DVD writers became the default of a PC's optical drive. Then again, given how cheap blanks are, unless your consistently getting coasters, I fail to see why one would compalin about getting one(If your getting coasters from bad Blu-Ray burns, that might be worth complaining about as BD-Rs were still ridiculously expensive last time I checked). Still, if your getting an unacceptable number of coasters when the image is good and no one else is having similar problems, I'd say that's a good indication the problem is either with the blanks you are using or the equipment your using for the burn.

Harry Kuhman
08-16-2014, 09:07 PM
I'm not going to get into a religious holly war with someone who is so certain of his "information" but doesn't seem to have anything to back it up except positive hopes. I also doubt that most readers here know exactly what dye type is used on their Verbatum disks. If you want to believe that Sony discs made in Japan are great but others are junk, I can show you images of Sony discs made in Japan that, within months of first using them looked like frost on the window on a cold winter morning, (and, of course, lost all of the data written to them) some even looked that way as soon as the single package plastic wrap was removed. This has occurred with multiple batches with different product numbers and different labeling, and to a friend as well as to me, indicating that it is not just the environment that I stored them in. It has never happened to me with other brands, only Sony. ImageShack seems to have lost that image, as well as my old free account, so here's a copy at an alternate location: http://i.imgur.com/m3Ut0zS.jpg

I suggest that anyone following this discussion don't take either of us on our word, but rather do some experimenting for themselves. You can track down the tool of your choice for detecting soft errors, I use "VSO Inspector". Then make multiple discs from your ISO. I suggest burning at 4x for a DVD and 4x to 8X for a CD. Go ahead and burn another copy at the maximum rated speed of the media and drive. Label them as to burn speeds and then test each for soft errors. For extra credit, keep both discs around and then do the same tests in six months and a year to see how the slow speed burns compare to the high speed burns for bit rot.

Over the years I've had this discussion many times, either with users who had discs that would not boot at all, or in at least one case I remember the user mentioning how painfully long it was taking to boot Knoppix. Suggestions to burn at low speed are usually resisted, but there are many old posts in these forums where someone has come back and acknowledged that a low speed burn was all that it took to correct their problems.