I have an HP 533w Pavilion. After 45mins to 2 days the machine will shut itself off but you can still hear the hard drive spinning and the power supply is still on. If I pull the power cord and plug it back in. I thought at first the video card was the problem and replaced it. That didn't fix anything. I've tried 3 monitors and they all eventually do the same thing. Thus ruling out the monitor issue. Thanks in advance.