[font=trebuchet ms]Whatever is causing the trouble is intermittent. That makes it hard to nail down because you can't find it unless it misbehaves while you're looking at it. I'm guessing there's a loose connection somewhere in the power supply wiring. This is dangerous stuff to mess around with. Unless you have some training in this kind of thing, I suggest it's time to take it to a qualified tech for a look-see.[/font]