System shuts down after short idol

[Joel]

When my computer is idol for about ten minutes it shuts
down completely and then reboots.If i let stay that way
it will continue to shut down and reboot. I played with
power setting and screen saver to no avail. It is a desk
top system. Any advice would be welcomed
Joel

 

[oldone]

Sounds like a power supply or overheating problem. Can
you check if your fan is working?