Did you ever resolve this? I rebuilt my power supply which seems to have helped, but every once in a while it seems to still happen. Owner I bought it from said it didn't have a soundboard when he bought it so he bought a soundboard from a checkpoint (probably removed when the 5v got low, and this resolved it since it took the load off). Said he had a friend burn the roms, but had to do it more than once (first time it didn't take). Don't think it's related.. I'm thinking my used board may need the amplifiers rebuilt?