No content symbol displaying

After restoring 2-3 times and deleting all backups and apps this problem does go away for a bit but it just comes back after a while and its really annoying.

Its the 'no content' sign displayed on the iPod app of my iPhone 3GS.
Its just saying it cant find any songs, podcasts, videos etc.
Under my iTunes and in the phones memory i know it is full of content.

Im on the latest version of itunes and iphone firmware and on this occassion
cant even seem to get the content back up, usually i power off and reboot and re-sync and if im lucky it'll work, this time nothing. Please help!