Virus anyone? Do a scan or two. Also, do a checkdisk, and make sure that there aren't any shorts (I've seen some power switches short and restart the comp). As for the sound, it isn't a beep code, because it's coming from the speakers. Maybe just the noise that was playing when it froze, is it the same tone everytime? I'm thinking a new mobo will fix it real quick, and if your mobo is as old as mine you need a new one anyway.