If your PC works at your friends house, but not at your house, you have something wrong with your power.
Do what johnny suggested - try a different outlet on another circuit.
If you live in the U.S., buy something like this:http://www.amazon.com/Electrical-Receptacle-Outlet-Ground-Tester/dp/B0012DHVQ0
Google "outlet tester".
$6 - $12 at a local hardware store.