Strangeness: I plugged my iPhone into the computer to sync and charge, then went to bed. While falling asleep, I heard the chime of my Mac rebooting. This morning, iTunes is up again, and it's complaining about tunes of mine not actually being there, while in fact they were.

Very strange. There was no evidence of what in the logs. It was just humming along like normal and then there were log events for the machine while it was rebooting.

My only hypothesis is that something went wrong with my external Firewire drive. That could have caused iTunes to be unable to find the music files and could also have induced the reboot. The state, in the morning, was that all of the files that were to have been synced had a "!" next to them, even though they were all there. Click on one and it played the track just fine.

iTunes, naturally, once it decided the files were unavailable has no way for me to have it do a bulk rescan or anything. (Does it?) Nor will it bother to check again if I try to sync again. *sigh*