This isn't a really big problem, but it's annoying when it happens. I came back from lunch, only to see iTunes frozen still. I leave it running 24/7, and have my music on an external 120GB firewire HD. Anyway, it's still showing in Play mode, but nothing is working; I have to force quit it because it's not responding. I relaunch iTunes, but it won't come up & gives me the error that my Library file is locked & cannot be accessed. I resort to turning restarting my computer at this point, and my HD doesn't show up at startup. I then must turn off, then turn back on my HD to get it to show back up again. Now things are back to normal. Anyone know what causes this?