Your power supply, or corrupt system files. If the power supply has such little wattage, even running the basic computer would shut it off, How many Watts does your PSU have?
what do you have running on the psu, is it under a heavy load (lots of ide drive, hdds, top end graphics card)?
have you changed anything recently?
have you ran antivirus, antispy software.?
what is the spec of your machine. Your temps are a okish,
Am I correct in converting 53deg Celcius to 127deg F?
If so, that is pretty high for a CPU...go to your CPU Manufacturer's manual or website to see what the safe temps are for your processor. It's been a while since I've looked that up but 127 seems pretty hot.