This has happened a few time now since updating to Gingerbread. A few times I've just heard the reboot jingle when the phone's been sat in my pocket but I've caught it in the act twice today. It locks up, blank screen but audio keeps playing ( Mixzing playing aac format if that's relevant ), ignores all button presses then after a couple of minutes just restarts. It can't recieve phone calls when locked up - I've tried phoning it. No data lost as far as I can tell. It seems to be getting more frequent. Never happened with Froyo but I'd not tried AAC files then ( that's the only thing I'm doing differently ) Any ideas?