Weird for a board to fail like that, usually it would be all or nothing, or at least a consistent problem.
How old is it? If it's old enough to still use the kind, I'd check for any burst capacitors
(especially if I was made before ~2007), or if not, general blown components. If it's not the bios, it may be a component failing, but only intermittently/with a certain load.
Doesn't help you in fixing it, but at least you'll know it's the board.
There are 10 types of people in the world: those that know binary, those that don't, and those that didn't expect this joke to be in base 3.
[video =373,150]http://a.pomf.se/ixefrf.webm[/video] Now shhhh Kaelan... OOOOOOH
pomf.se is ded. :'(