I replaced the power supply once before because of a problem. At that time it was starting up for about 30 seconds and system BEEP would activate and go back off. I could press reset on the front a couple of times and it would start up. but would not go on and off with power supply turned on and then back off.now there is  no beep,and shorter time on and back off. This is the key difference. I believe something ELSE has fried this time. But, a bad power supply would be the lesser of two evils. It happens during the day while I am at work, and that is the normal time the power goes off. I have spike and surge protectors. Tennessee valley authority and Georgia Power are terrible about this issue. Thanks again. No overclocking at all on this system. Cat hair problem sometimes.electricguru.....Have you tried opening up the pc and removing the cat hair and fur balls ?
Have you tried the nose test ........ open it up and try to start ....is there any burnt odor ........?

DL65  
Bloody smeg! Either STICK to one threat or PM DL65.