OS is Vista Home 64 This computer is a fellow worker of mine who said he was online shopping at Ebay when his computer crashed. So, I am currently working on a computer issue that is, starts up and then shut down right as it's loading the OS then it will try and try but sometimes it don't even make it to the loading OS screen. Here is what I have done so far, checked the power supply with a mulit-meter things look good, then I put a new thermal compound on his cup/heat sink. Note* the power button doesn't work all the time unless you take off cover and push back on the button in order for it to work. This has been broken for a long time according to him so I don't know if that's the issue or not? My thoughts are leaning towards the power supply.