So my partner updated his iPhone 4 to iOS 5 the other day. He is running iTunes 10.5, Lion 10.7.2 and stores all his music on an external hard-drive that he connects to his computer whenever he uses iTunes. For some strange reason, when he updated to iOS 5, no music whatsoever synced over to the phone. All that appears on the iPhone are greyed out song titles that you can't select. The iPhone says that it's got the songs there and that they're using up the capacity of the phone, but he can't play them because they're greyed out on the iPhone when he tries to select them. We've tried restoring the iPhone from backup (3 times), unsyncing music and then resyncing it, etc. but nothing works. I thought maybe it had something to do with the fact that his music is on an external hard-drive, but his music always used to sync before and iTunes still plays the music from the drive. Can anyone help? What should we do to fix it? It's kind of annoying that to listen to music he now has to carry around an iPod when he always used to use his iPhone for music.