rjarvis:

The key to your issue might be that it is a Sony laptop. They tend to use a particular vendor's optical drives that have been known to have issues reading certain DVD media. If it is a QSI drive, then you might need to use DVD+R media, instead of DVD-R. I also have several Sony notebooks and this is the exact solution I have found. Also be certain to burn the DVD at no higher than 4X, if not slower. Use good media also. It does make a difference. If you hold some of the "Bad" disks up to a good light source at an angle, you can usually see imperfections towards the outer edges of the disk. You might also want to check your ISO file for errors by using an MD5 tool to verify it. There is more information on this in the documentation section on this site.

The DMS cheatcode might also be helpful, but I have not needed it for my Sony laptops.

You might also want to try some Windows based tools on your drive, like the recovery console. It is usually not wise to write to an NTFS partition using Linux. It may corrupt the file system and render the partition unreadable. If you are using Knoppix in order to copy the files over to some other drive/system for recovery, then you are on the right track. If you need to boot into an XP environment, look up Bart PE. It's a useful tool for Windows machines using NTFS partitions. There are other live Linux diustribitions made specifically for Windows/Linux system recovery, and have some useful tools for those purposes also. Don't know if they are superior to Knoppix though, but they are available for download. Look at www.distrowatch.com or www.linux.org for info.

Good luck! Let us know how you make out.