Wrong section I believe, but I'll try to help.

Had the same issue with my girlfriend. I believe that when you register iTunes and your iPod on a computer, it locks it with that computer. Any kinds of uploads or edits to your iPod songlist or information will have to be done on the original computer you hooked it up to.

I'm sure that there's some way to get around that, but I don't know what it is. Someone else on here might. Good luck.