The weirdest thing just happened - I was syncing my iPhone, clicked the X in iTunes to cancel it, iTunes froze on me so I just slide on the iPhone to cancel it. iPhone acted fine but iTunes still was unresponsive, so I force quit it. When I re-opened, I lost over half my music (artist names A-O). What happened? Is this a common problem? It's getting a bit annoying to keep re-upping 10+ GB of music...