You may have a ground loop problem . You said you were watching the Pistons Heat game and there was a hum . So I take it you have cable or sat. hooked up to it some how or another . Try unhooking the coaxial cable coming in from the wall outlet . You know the cheap screw on connector . If you do have this type of connection through a cable box or sat. rec. it is often the culprit . If this is the source of the problem you may need a ground loop isolator .

check the link

http://www.mitcables.com/products/products.asp
( search for ISO-LinQ must be spelled this way )

http://www.elect-spec.com/video.html