Recently I had a coworker who upgraded his iPhone to 3.0 find that he could no longer sync that iPhone with his iTunes music library on a Windows computer. It would, however, sync just fine on a Mac OS X computer. Also, it was correctly syncing other items, such as his app store applications.
Googling turned up a few suggestions that we tried:
- Turning off the phone
- Removing all music and re-adding it (ie, remove from iTunes DB, NOT from the hard drive!)
- Resetting iTunes sync settings (preferences->devices then clear sync history or forget all remotes)
None of these worked, but we did find the answer with a last resort effort.
Solution: Uninstall all Apple software (you probably only needed to uninstall iTunes, but this is what we did) and then re-install iTunes.
This uninstall/reinstall should allow you to again sync an iPhone with your music library.