Maybe a problem of linux not mounting the drive as a virtual scsi, If I'm not wrong that is the way the cdr program in linux work with ide cdr drives. Check the cheatcodes, there's something like "ide-scsi=/dev/hdx" to force a drive into scsi emulation, I don't remember exactly how it was.

Alternatively, here's another solution:
A) Find someone you can borrow an USB drive from, or another recordable media that knoppix could use. The bigger the better. If the collection is huge, try to find a Handydrive or a backup tape unit.
B) Boot from knoppix. Mount both the damaged partition and the device.
C) copy the files to the drive
D) delete the partition, create a new one, format, place the files on their original place.
E) remove the sweat of you forehead, your mp3 apocalypsis is over! :P

The CDR is a good bet, and you will have a safe copy of you mp3
(...I'll supose they are a legal backup of your music CDs, isn't they? )