From Knoppix Documentation Wiki
This FAQ is comprised of both downloading & burning questions.
- This FAQ translated into other languages. May not be current or in sync with this FAQ
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Q: Which version is the newest and which should I download?
A: As of September 2011 the current release is 6.7.1. Versions sometimes change frequently, but the newest official versions should always be on the official BitTorrent Tracker, so get the most current status of version information there. They usually show up shortly after on most of the Mirrors also, but some mirrors may take a week or more to update. Sometimes unofficial releases also come out, recently these have been copies of versions of Knoppix released for magazines or trade shows. Use these unofficial versions at your own risk.
Official versions of Knoppix will have both a version number and a release date in their name. Some versions of Knoppix had several releases with different dates for minor bug fixes but did not change the version number, so checking the release date may be important. Versions of Knoppix will have either CD or DVD in their name, indicating the size of the distribution and the intended media for writing the ISO. The CD version is prefered by many users who wish to carry a Live CD and be able to use it on almost any system that they try to boot it on.
Most of you needs the "KNOPPIX" and not "ADRIANE-KNOPPIX" version. "ADRIANE-KNOPPIX" is a special version for blind people.
The file names (before the ISO extension) will end in either DE or EN. The DE version will by default boot into German. The EN version will default to booting into English.
Most mirrors also contain some older version of Knoppix. There is currently no known website that offers all old released versions of Knoppix.
Q: How do I get the CD/current beta?
A: Several possibilities:
- Download with Bittorrent from The Unix-AG BitTorrent Tracker. Get BitTorrent (if you need it) from http://www.bittorrent.com/. Be sure you set up your firewall setting properly. Properly configured BitTorrent will usually download Knoppix much faster than getting it from the mirrors. "Magoo's Complete Guide to BitTorrent and BitTornado" will help you configure it & get it working. BitTorrent is by far the fastest and most reliable way to download the ISO. See this thread for one discussion of that: http://www.knoppix.net/forum/viewtopic.php?t=25708
- Download from one of the mirrors listed at The Knoppix Download Page. Try to choose the mirror nearest you for best results.
When downloading from a mirror, be sure to also get the matching md5 file. When downloading with BitTorrent you get a set of all related files in one download.
- If you download the ISO image file from a mirror, then also download the accompanying MD5 file too. If you download by BitTorrent then you will also get an md5 file automatically, although BitTorrent has its own checks and the md5 is only a second recheck of a good download.
- Order a CD. If a 700Mb download is too much for your bandwidth capabilities, you can order the newest CD from a retailer on The Knoppix Order Page
Q: Can you download Knoppix in parts if you have a low bandwidth (28.8 Kbps) such as pausing the download and continuing it another day?
Q: I can't write to my hard disk while running Knoppix from cd. How can I save the .iso file?
A: Try downloading to a 1gb (or larger) USB jumpdrive.
Q: What are these strange MD5 files that accompany the ISO CD images?
A: The files with the .md5 and .sha1 extensions contain checksums for the actual CD ISO images. A checksum is a way of fingerprinting files. Just like a real fingerprint identifies a single person, a checksum is unique and matches exactly one file. It is used to verify that the file downloaded matches the original all the way down to the smallest details. In the case of downloading a Knoppix ISO image, the MD5 and SHA1 checksums are used in order to verify that the file downloaded is perfect and not corrupt.
Many file corruption problems have been observed when downloading from the mirrors. It is very important to check the md5 checksum if you use a mirror rather than BitTorrent.
This discussion is about a separate md5 file that you can download from the mirror that you got the Knoppix ISO from, or that comes down as an individual file in the package of files that you get in the package when you download with BitTorrent. DO NOT extract any md5 file from inside the ISO. The ISO does contain an MD5 file that is used by the testCD command, but this is not the file that is discussed here and should not be used to test the ISO download.
When you download both the ISO image for the CD, you also must download its corresponding .md5 file. The .md5 file is a plain-text file and can be viewed in a text editor or web browser.
- When downloading and running under Windows, you can check the md5 checksum with your choice of many programs, several of which are listed below. Please note that the methods to check the ISO file & verify the checksum will vary between programs.
- When running under an already booting copy of Linux you can verify that your download was perfect and that the ISO's contents are unchanged by typing "md5sum -c filename.md5" at a Linux shell prompt (command prompt). Knoppix includes the program md5sum, with some versions of Linux you may need to install it. Note that this is a command for use in already working Linux systems, it is not a Knoppix cheat code for use at boot time.
- Detailed instructions for checking an iso file against its md5 hash from linux (knoppix):
- first download the .iso disk image file and its .iso.md5 (or .iso.md5.txt or .iso.md5.asc) hash file;
- open a shell prompt window, such as konsole (the blank monitor icon on the panel bar at the bottom of your screen);
- the shell prompt works much like the command prompt in dos/windows. Moreover, the commands cd (change directory), dir (list directory contents), help (list commands), and exit, are essentially the same as in dos;
- change to the directory where you saved the .iso file and .md5 file;
- use "cd /home" if you saved to your home directory, use "cd /media" or "cd /mnt" to change to the mount point for hard drives and flash memory, "dir" will list devices that are mounted here, "cd hda2" will move to the 2nd partition on drive a (the 1st hd), "cd .." (note the space) will move up one level to the parent directory;
- in linux file and folder names are case sensitive, so "knoppix" is different from "Knoppix" and from "KNOPPIX";
- use the md5sum command with the -c option to check the .iso.md5 file hash code against the calculated hash for the .iso file (the response may take a minute or two);
- use "md5sum -c KNOPPIX_xxxxxxxx.iso.md5" (or .iso.md5.asc), to check against the listed .iso file in the same directory, (remember names are case sensitive, and replace "xxxxxxxx" with the version from the file name);
- if the .md5 file contains a list of file names and hashes, you will see "file not found" messages for other files, look for the specific .iso file name that you downloaded for the relavent response (which hopefully is "OK");
- use "exit" to leave the shell prompt, and procede to burn your cd (or to re-download the .iso image file if the md5sum check failed).
- Note that checking the sha1 hash works the same as above: use "sha1sum -c <filename>.iso.sha1", using the .sha1 hash file that you downloaded with the .iso image file.
Further information about MD5 and programs for various OS's can be found at The MD5 Protocol Documentation.
Q: What are these strange ASC files that accompany the ISO CD images?
A: Most users can ignore the .asc files. If there is ever an uncertainty as whether or not the ISO image file and its accompanying MD5 file are originals & untampered, then the .asc files are important. The .asc files are digital signature messages. Digital signatures are a method of authenticating digital information similar to ordinary physical signatures on paper, but implemented using techniques from the field of cryptography. With this you can be sure the ISO image and accompanying MD5 file are genuine, because the .asc file containing the MD5 is signed with Klaus Knopper's PGP key. To verify the file, you need to import PGP key ID 0xBA8F038D from your favorite keyserver, then in Linux you can type "gpg --verify KNOPPIX_Vxxxxxxxxxxxxxxxxx.iso.md5.asc". Then you must check that the MD5 checksum in the .asc file is the same that the MD5 checksum in the .md5 file.
To download the keys, type:
gpg --keyserver pgp.mit.edu --recv-keys BA8F038D
If you want to verify the signed md5 file and the ISO file in one step, you can type:
gpg --decrypt KNOPPIX_Vxxxxxxxxxxxx.iso.md5.asc | md5sum -c -
Q: I downloaded a file but it is a ZIP file, what do I do with it?
A: In all likelihood, you do not have a ZIP file. No offical source is providing the Knoppix files in ZIP format and it is unlikely that unofficial sources are either. From past experience we know that is is most likely that you are allowing Windows to hide file extensions from you and you only think that the ISO is a ZIP file because of an ICON accociated with it. Windows should never be allowed to hide file extensions. Go to My Computer -> Tools -> Folder Options -> View and turn off the "feature" that hides file extensions (It may be -> View -> rather than -> Tools -> for some versions of Windows).
If you have "extracted" any files from the file that you thought was a zip file, delete them. If you have deleted what you thought was a zip file (the ISO file), you will have to download it again. You can not put the files you extracted back together and make another ISO, parts will be missing.
Q: I downloaded a file but it is a RAR file, what do I do with it?
A: In all likelihood, you do not have a RAR file. No offical source is providing the Knoppix files in RAR format and it is unlikely that unofficial sources are either. From past experience we know that it is most likely that you are allowing Windows to hide file extensions from you and you only think that the ISO is a RAR file because of an ICON accociated with it. Windows should never be allowed to hide file extensions. Go to My Computer -> Tools -> Folder Options -> View and turn off the "feature" that hides file extensions (It may be -> View -> rather than -> Tools -> for some versions of Windows).
If you have "extracted" any files from the file that you thought was a RAR file, delete them. If you have deleted what you thought was a RAR file (the ISO file), you will have to download it again. You can not put the files you extracted back together and make another ISO, parts will be missing.
Q: I have downloaded the ISO file. How do I burn the ISO? How is the ISO supposed to be burned?
A: First check to see if the ISO that was downloaded is perfect & not corrupt. See the above FAQ labeled #Q: What are these strange MD5 files that accompany the ISO CD images?. If it passes the MD5 checksum then you must burn the ISO as an image.
If you have a cd-rw (re-writable) drive, you should opt to use cd-rw disks, saving you from wasting disks and allowing flexability. If you have a cd-r (recordable) drive you will need to use cd-r disks. You will need one 700MB/80min blank CD-RW or CDR disk.
- You can use the command cdrecord or the CD burning program K3b (under "multimedia" in the "K[gear] menu).
- Quick answer: Use a program such as Nero Burning Rom or Roxio CD Creator. You can get a free trial of Nero from their site. In most cases you will want to skip the burning wizard and choose File -> Burn Image or File -> Open. Select the KNOPPIX_Vxxxxxxxxxxxxxxxxx.iso file, then -> Burn.
- Long answer: Of course the answer depends on the individual program you are using to burn CDs, but all common CD-Writing programs should support the option of burning the ISO as an image, you probably just have to find the right menu option. In the burning program, do not drag & drop the ISO into the burning screen. In the windows explorer, do not attempt to decompress the ISO with something like WinRAR or WinZip. You must CHOOSE to burn it as an image. Do not burn it at a fast speed greater than 16X. You must burn it at a very slow speed preferably 4X or 8X. Burn your CDR as a "Single Session CD" or select finalize. The Mode "Disk at once" or "Track at once" should not matter (have a look at the Online-Help of your burning software).
- Windows XP/2003 only
- Install the ISO Recorder plug-in for Windows Explorer. Once installed you merely right-click on the ISO image and choose "Copy image to CD".
A common mistake made when burning ISOs: "I downloaded & burned the ISO to CDR as a bootable data disc. Now it boots to a A:\ Caldera DR-DOS prompt." You are probably seeing something like:
Caldera DR-DOS 7.03 Copyright (c) 1976, 1998 Caldera, Inc. All rights reserved. [DR-DOS] A:\]
This means that the ISO was burned as a bootable CD or bootable data disc. A Knoppix ISO already includes the boot instructions so it is not necessary to burn it as as a bootable data CD. Burning the ISO file as an image will automatically take care of the bootable details.
It is also possible to burn a bootable Knoppix CD using a Mac. After you have downloaded and verified the .iso file, open Disk Utility from the Utilities folder. Choose Burn from the Images menu and select the .iso. The resulting disk will be bootable on most PCs, the same as if you had used another iso-burning tools.
- Guides and Tutorials
- Quick walkthrough example burn Nero Ultra Edition 188.8.131.52 (not Express.)
- I run it and it automatically starts a "New Compilation" wizard. I immediately click Cancel. Then I go to the File menu and choose Open (or I could just use the keyboard shortcut of CTRL-O). In the Open file dialog box, I change the Files of type from "All Nero compilations and Images" to "Image Files (*.nrg;*.iso;*.cue)". Then I go find the Knoppix ISO file and double-click it to select it. It then brings up the "Burn Compilation" dialog box. I choose a write speed of 4x or 8x. I check-mark the "Finalize CD (No further writing possbile!)". I personally choose the write method of "Disk-at-once" but I know that "Track-at-once" also works. When I am ready, I click on the "Burn" button and Nero will burn the Knoppix ISO to the CDR.
Q: How do I burn an ISO to a CD using NERO?
A: There are different answers for different versions of Nero.
For Nero 5, start the program. You can just hit CANCEL at the wizard menu to get to the main window. Ues the FILE option in the menu near the top of the screen and select the Burn Image ... option in the sub-menu. Find the ISO that you downloaded in the file open box that pops up. Burn at a slow speed. Do not drag and drop the ISO into the file area. Do not take any option to make the CD bootable.
For Nero 6, full version: The Burn Image ... option in version 6 is gone. Use one of the following: Get to the main menu and then use the Open .... choice under the FILE menu, or under RECORDER in the top menu you will find that Burn Image ... has been moved to this menu. In either case use the box that opens to find the ISO file that you downloaded. Burn at a slow speed. Do not drag and drop the ISO into the file area. Do not take any option to make the CD bootable. When burning with Nero 6, be sure that the option that does a verification check after the burn is enabled (This is true for any software that has this feature, not only Nero 6).
For Nero Smart Start: If you are stuck with this version of Nero, start the application. Point to the 5th icon across the top (the one that shows 2 CDs over a box-like thing). Choose Burn Image to Disc from the menu that changes below the icons. Find the ISO that you downloaded. Burn slowly.
For Nero Express 6: Under the question "What would you like to burn?", pick the last option, Disc Image or Saved Projects. Use the box that opens to find the ISO file that you downloaded. Burn at a slow speed.
If you do not have a copy of Nero you can download a limited time trial version from Ahead Software. This should give you plenty of time to burn your first Knoppix CD. After the trial expires, if you do not choose to buy Nero you can use Knoppix itself to burn future ISO files.
Q: How do I burn an image on to a CD using B's Recorder Gold from BHA?
A: Close the Wizard dialog if it pops up when you start the application. Drag the KNOPPIX-*.iso file to the lower RIGHT region of the app window. It is shaded in yellow and has the title "Track Type"(The icon with a musical note and a folder will be seen in the middle panel). Right click the left region where it says ")1 DATA -mode1 and from the popup menu choose properties. Choose "ISO compatible" and "create from standard bootable disk image" in the two selection boxes. Then press the record button (Upper left), pick your options, and Voila - one KNOPPIX bootable CD is yours.
Q: How do I burn an ISO to a CD using NTI CD-Maker from Brouderbund?
A: Start NTI. Tell it you want to make a data CD. From the FILE menu near the top of the window, select the sub-menu option "Create Disc from ISO Disc Image File ..." and find the ISO file in the resulting search box that opens. Burn at a slow speed. Do NOT Drag and Drop the ISO into the file area.
Q: How do I burn an ISO with the Microsoft burning software that comes with XP?
A: Burning an ISO is not supported in the Microsoft software. Many OEM that package XP with a computer also include other burning software that will burn an ISO. There are third party free and trial version programs that will burn an ISO file under XP that you can download. For example, ISO Recorder is a plug-in for Windows XP that will enable burning an ISO image. A free trial version of Nero is available from Ahead Software.
Q: How do I burn the .iso.md5, the .iso.md5.asc the .iso.sha1, the .iso.sha1.asc, and the MD5SUM files to the disc?
A: These files are not intended to be burnt to the disc, they are only provided to let you verify that the download that you received is good. If you have not yet checked the md5 checksum as described above then you are not ready to burn the disc. If the md5 has been verified and is good then you no longer need these small files. The other files are provided as alternate ways to check the file. If you already use sha1 checksums you can check that way instead of using the md5, here we keep things simple by only focusing on the md5, either test is completely valid and you need not do both.
Q: I have a fast access to a Knoppix-mirror. How can I burn this ISO-file directly to CD-RW with GNU/Linux?
- - mkfifo KNOPPIX.fifo # mkfifo create a fifo-file
- - screen ftp mirror ....# screen creates multiple shells in one terminal (handy!) ftp connect to your mirror...
- get KNOPPIX-3.10-EN.iso KNOPPIX.fifo #command to copy inside your ftp-session
- - C-a C-c # screen will make a new shell
- - cdrecord dev=(your burner) speed=4 KNOPPIX.fifo # ftp starts to get data when cdrecord starts to read from fifo
- wait; exit; rm KNOPPIX.fifo; exit
(Attention, use "cdrecord -scanbus" before cdrecord to find the correct device of your cd-writer. If you own SCSI hds, you could lose all data of one hd when you use cdrecord with a wrong dev=(controller,id,partiton) !)
This works well and is much simpler: wget -O - URL_OF_IMAGE | cdrecord -v speed=4 -eject -
Q: What should the resulting disc look like when opened under Windows?
A: If you see one ISO file on the CD or DVD then you burnt the disc wrong. You should see an entire file structure on the disc. This may vary somewhat for different versions of Knoppix, but for the 5.0.1 CD version there would be a boot folder with files in it, a Knoppix folder with files in it, several autorun files, a cdrom.ico icon file and an index.html file.
Q: What option do I use to make the CD (or DVD) bootable?
A: None! Do not use any option in your burning software to make the CD bootable. Just burn the ISO as an image, this will put all of the proper files on the CD in the proper locations and the resulting CD will be a perfect copy of the original Knoppix CD and will be bootable. If you take any option that makes a bootable CD, you will end up with a CD that does not boot into Linux/Knoppix.
Q: My computer won't boot from CD. What should I do?
A: Look in your computer's BIOS (on many computers you need to push the "delete" or F1 key during the POST) to see whether it is set to boot from CD. If this is already set, your computer may not be able to read the CD (some notebooks have problems with black-coated CD's, for example). Some computers will only use the new BIOS settings after a hard reset. Other resources are this page which explains the PC BIOS and this page explains the boot order.
Smart Boot Manager
If your BIOS does not support booting from a CD at all, or if it has that feature but doesn't seem to recognize the Knoppix CD as bootable (and you believe that you burnt it properly), there is a tool called Smart Boot Manager. Get the Smart Boot Manager installer, and install SBM to floppy, this should let you boot from any bootable CD. Download Smart Boot Manager. If you want to install from windows, download the sbminst.exe and run it from the Command Prompt like : sbminst.exe -d 0 to install to floppy drive. SBM can also be install to your hard drive's Master Boot Record, so you will not need a floppy at all to boot the CD.
- Note: Smart Boot Manager does not support SCSI, so if the CD drive that you can't boot from is SCSI, this method won't help.
Another really nice boot manager that will let you boot a CD on a system where the BIOS does not support it is XOSL. XOSL is slightly more work to set up, but it is much more powerful and has a much nicer looking user interface. It uses SBM code internally to boot the CD. XOSL must be installed to hard disk, it will not fit on a floppy. For Linux users it is often best to give XOSL its own small partition (just a few megs in size). Both XOSL and SBM will let you select at boot time from multiple Operating Systems stored on your hard disk(s). When using XOLS or SMB that way (with either installed to hard disk), install the Linux boot manager (usually Lilo or Grub) to the Linux partition, not to the MBR.
Q: My PC will boot off of the burned disc. It is strange since it loads but then stalls or it loads but is giving me I/O errors. What's going on?
A: You possibly only got a partial download or the download was complete, but corrupt. If this is the case, then the ISO image is defective and the CDR burn of Knoppix is also defective. This is because the data in the missing/changed parts cannot be accessed (sometimes one can even "hear" this because of the sound the CD-ROM drive makes due to repeated read attempts). It appears to work because the directory tree is written at the beginning of the CD and can be correctly read. However, reading the actual contents of the missing/changed parts is impossible, or in other words, accessing the contents fails. If the ISO image was checked & found to be unchanged and not corrupt, then it is possible that the CDR has been improperly burned or a bad piece of CDR media was used. To rule out the possibility of a bad download or a bad burn, some solutions can be found in the section Q: What are these strange MD5 files that accompany the ISO CD images? and Q: I have downloaded the ISO file. How do I burn the ISO? How is the ISO supposed to be burned?.
Problems are often seen booting with discs that have been burnt at a high speed. If you checked the md5 file and know that you have a good download of the ISO, and you have followed the other instructions for burning the CD as an image, then be sure that you burn the CD at a slow speed, either 4x or as slow as your burner will let you go (some new burners and newer burning software seem to refuse to burn slower than 8x). High speed burns may work on some systems but not on others, so saying that you high speed burn will boot on one system does not offer proof that is is a good burn or should be expected to boot on other systems. There are also reported cases of the CD working but the boot taking much longer that it should for the system to finish booting. These problems are resolved by a slow speed burn.
If the ISO is good and the burn was done properly and at a slow speed, but Knoppix doesn't seem to be able to boot on your hardware, you may need to use one or more parameters to help Knoppix if it can't determine your hardware configuration on its own. We call these extra parameters "cheat codes" (see the Cheat Code FAQ for details). In rare cases you may have an optical drive hardware problem (sometimes using CDRW media rather than CDR will help work around this), and sometimes the dma "cheat code" can help a optical disc boot properly (or the nodma "cheat code" for some versions of Knoppix around 3.7). And be sure that you system is up to Knoppix's minimum requirements. A slow and memory starved system will stall when booting and come up very slowly.
Q: I know that my disc is good because it boots on another system. Why will it not boot on this computer?
A: If the disc was burnt at high speed you do not know that it is good! We have seen over and over that discs burnt at high speed will boot on some systems but not others, or cause other strange problems when booting on some systems. The disc should be burn at slow speed, as suggested elsewhere in this FAQ. If the disc was made at slow speed and the md5 checksum was good and the disc passed a verify pass in the burning software, you may need one or more "cheat codes" to help the hardware detection process along.
It's worth mentioning that you just might have a memory problem. The Knoppix disc includes a bootable memory test that will check this, just type memtest in at the boot prompt to run memtest86. If you can't even boot into memtest86 then something is very wrong with the disc that you made or with your system, if memtest boots then you can determine if your memory is good (and if you have as much memory as you think you have).
Q: Why does my writer/software not accept to write to my 80 minute CD-R?
A:Some older writers or older versions of writer software cannot recognise the new playing lengths, because the groove is laid more narrowly. Check with your hardware and software manufacturer to see if these newer media are supported. In most cases, updating the writer software's current firmware (check out the web site of the software manufacturer) will solve these problems.
Q: What to do if I haven't got enough space on the CD to burn Knoppix on it?
A: There was previously a response here that said "You can overburn it (http://www.wikipedia.org/wiki/CD )". That is the wrong answer! If the file is correctly downloaded, it will fit on a 700 meg CD (check the md5-sum!!!). It will NOT fit on a 650 meg CD, not even with overburn.
There seem to be a lot of people who are confused about the size of the ISO-file. They either look at the size in bytes and think it will not fit (forgetting that 1 meg is 1024x1024 bytes), or they have done something else wrong like "unpacking" the ISO and then trying to burn it. Most people who report that the ISO will not fit on the CD, will never report back what they did wrong, once they resolve the problem. But the bottom line is that if you properly confirmed the md5-checksum, and saw one good ISO-file (not multiple files), then the file will fit on a 700 meg CD if burned properly.
Q:Why do 750 MB fit onto an audio CD but only 650 MB onto a data CD?
A: A sector of a CD consists of 2352 bytes. With an audio CD, these are used completely for audio information. With data CDs, an additional fault correction is inserted, and the usable capacity shrinks to 2048 bytes. A 74 minute CD consists of 74x60x75 = 333000 sectors. With 2048 bytes per sector, this gives a usable capacity of around 650.1 MB, with 2352 bytes per sector it gives around 746.6 MB. This therefore also produces a difference in data rates for reading/writing: 172 kbps with audio and 150 kbps for data.
Knoppix needs a 700 meg CD or CDRW to burn the CD. It wil not fit on a 650 meg CD.
Q: After I've used KNOPPIX, my "other" OS suddenly shows a blue screen with the message "File kernel.exe not found or defective" and "reinstall..." shortly after boot.
A: Simply take the KNOPPIX CD out of the CD-Rom drive and restart the computer.
Q: I can download the CD. Why can't I download the DVD? I don't get the proper sized file.
A: Since the release of the Knoppix 5.0.1 DVD ISO-file, some people have expressed surprise about this, although many of us expected it. There are some common problems:
If you are trying to save the DVD ISO-file to a FAT32-partition (such as used by Win98), it simply cannot be done. The 5.0.1 DVD ISO-file (and very likely later DVD ISO-files) is larger than the maximum file size that can fit on a FAT32-partition.
If you are trying to download to a Windows NTFS-file system partition or a Linux-file system partition that supports files over 4 GB in size, but you still get a bad download there are two more common problems. Both problems would be avoided, if you use a current release of BitTorrent and download with BitTorrent, rather than use a mirror.
The first problem occurs if you are getting files just under 4 gig in size or extremely short files (around 50 megs for version 5.0.1). In this case the downloading software that you are using is not capable of downloading files larger than 4 gig. One good thing here is if you now have a file just under 4 gig and you try to download with BitTorrent to the same directory, BitTorrent will often detect the file, check it, and download just the missing part (for this to work the downloading utility that you used should not have changed the file name and not otherwise have modified the file).
The second problem is corruption of the mirrors, that has been seen before. In this case your download file will usually actually be slightly larger than the expected file size.
The bottom line is to always check the md5-checksum before burning and learn to use BitTorrent for a fast and reliable download.