Thanks, madofrain. That's really helpful. He has a lot of fake duplicates because of so many live shows, but he does have a PC so we'll try that option first and hope it doesn't take long for the fix to come along. 
Morning. yup Jacksam is right. formatting your pod to fat32 will also resolve it. By plugging your pod into a windows machine it will reformat it with windows firmware which your mac can still read. It'll just be slower transferring your files to it. Some people have reported some buggy behaviour but its still an option as the issue is just with the mac firmware.
Greenegirl:
Hello! The fix i applied to my machine involved migrating *all* of my files to a new user account under U.S english. I eventually deleted the old UK one. I synced my mail, adress, bookmarks etc with a trial .mac account and the rest of my files were moved to the 'shared' folder so i could access them with the new US english user i created.
A chap on the apple boards took it a stage further and completly reformatted his ibook. I just wanted to see if I could get away with a fix that side stepped the need to backup my data. Turns out it worked. :O) Its important that you leave behind the itunes xml and librabry files from the old user. The idea behind the fix it to rewrite these xml files in U.S date format.
Its also important to note that the -48 error in os 9 is listed in Apple's tech notes as duplicate related. So make sure you weed out ANY duplicate song names! even if they're live or single versions. I just renamed mine..
Granted its all alot of effort, but I was off work and had some time on my hands. The tech support agent assigned to this issue has reported that he's replictaed the error in the apple labs, so if all the user moving/file renaming etc seems a bit daunting there should be an apple firmware fix on the horizon..
P.S oh you might want to remove any odd charachters *^/ etc from ALL the song tags..comments,album, track title etc..These are xml control charachters and some people think they may be part of the problem. If you want any further help just ask. I'm away as of Saturday for New years celebrations but i'll be around until then.