My pc is 6 years old, RUNS great on windows 98. Recently, while using, it shuts down hard. I press the power button and nothing happens. I remove the ac cord, leave it out for a minute and plug BACK in and everything works fine again. It shuts down hard about 6 times a day. Bad PSU? What do you THINK?What make and model is it? (The computer and the power supply.) A PSU is a quick and easy upgrade, but it depends on what you have to know if proprietary parts are involved.

The symptoms you describe sound like PSU, heat or RAM, in that order. Are you doing anything in particular when it shuts down (gaming or light duty, or kjust sitting there?) The fact that replugging it makes it work again is another indication of PSU, but we need more details about the machine.It's an IBM Aptiva. I swapped out the PSU with the PSU of my EMachines. Voltages are the same as indicated on the PSUs. Didn't check them. Seems like the PSU was not compatible. When I installed it. WITHOUT PRESSING the power button, the HD would spin constantly but would not boot. Cabling seemed the same except of a power connector (P8) that went to the MOBO. The IBM didn't have a P8 JK. This happens when it is just sitting idle, but mostly when I'm downloading. I don't do games so light duty is all i need it for.Obviously all PSU's are not the same and wattage is not everything. Check eBay for an old machine that you can harvest from.