My wife's computer has developed a problem when it is powered off completely. It will power up for a few seconds then it shuts down for a few, powers up for a few, shuts down for a few. It repeats the cycle until you force it to power down by holding in the power button. The computer is about 1 year old and it has only done this twice in the last 3 or 4 months, but only when it has been powered down completely and restarted. Anyone had this happen or know where to start? I'm thinking power supply or motherboard, but maybe I'm off base.