I have two computers- one at home, one at work. Usually I add music at home, and bring it to the office. However at one point, I tried to move some music from the office computer onto the ipod. I got an error "Disk cannot be read from or written to", and then when I got it home, the SAME error. The itunes and OS's were at different versions at the time. No matter how many times I wiped and restored the iPod, things would go bad every time I tried to use it on both computers through iTunes.

I found that things work much better when you let one computer be the iTunes syncing "owner" of the iPod and on the other computer, do everything using a utility like iPod Rip. Otherwise things get damaged or corrupted. I ended up wiping the iPod, and designating "home" as it's master. Since then

More on this issue is here:
"Disk cannot be read from or written to" when syncing iPod or "Firmware update failure" error when updating or restoring iPod