A couple other things to try:
If ISO9660 doesn't work, try a Mac/PC data disk. Make sure for both of these you limit yourself to 8 letters in the file title and always make sure the .mp3 extension is at the end . Capital letters may make a difference... try all caps. Also, I would try at least at first having all of your files in the root directory. Hopefully one of these suggestions will help.
Cheers!
Chris