It can be either some bad sectors on the HD of your iPod or there are couples corrupted music files on your iTunes
For the bad sectors, see doing the following helps
For Mac computer
1. Open the disk utility, hope your iPod appears there (left hand side), highlight it
2. Go to Tab “Partition”, click either “Delete” or “Partition”, if fails, skip this step and go to 3
3. Go to Tab “Erase” , choose Volume Format as “MAC OS Extended (Journaled), and click Erase, again if fails, skip it and go to 4
4. Same as step 3, but open the “Security Options....” and choose “Zero Out Data” before click Erase. It will take 1 to 2 hours to complete.
5. Eject your iPod and do a Reset
6. Open the iTunes 7 and click “Restore”
For Window computer
Go to folder “My Computer”
Hope you can see your iPod there and right click on the iPod
Choose “Format”. Ensure the settings are at “Default” and that “Quick Format” is not checked
Now select “Format”
Eject your iPod and do a Reset
Open the iTunes 7 and click “Restore”
For corrupted music files on the iTunes, you have to find a way to find them out, and delete them.
Oh,one more thing, try to change your iPod drive letter and see if it helps
http://docs.info.apple.com/article.html?artnum=93499
