To be clear, I have a 160 GB (purchased last month), my brother has an 80 GB (purchased last year) and his girlfriend has an 80 GB (purchased last Christmas) and we all share the same library. We are all having the same issue, each with different songs, however. On the other hand, I have an older 60 GB iPod (purchased just before iPods could play videos) and this iPod does NOT have this problem.
We've tried re-synching, restoring, all to no avail.