Chosen Solution
My iPod (5th gen video 30gb) plays fine, and charges (by wall plug or pc) but won’t sync to iTunes to download more songs. My PC sees it but iTunes doesn’t. Any ideas?
Try using a new or different sync/charge cable. I would also check the dock connector itself for broken or dirty connectors.
Try resetting your iPod (no data is lost from device): http://support.apple.com/kb/ht1320 If that doesn’t fix it, reinstall iTunes and all its components: http://support.apple.com/kb/HT1923