*bump*
I've had similar problems if I leave my PC on for more than 24 hours, so far I've gotten:
WMPlayer stops responding
Yahoo Widgets stops responding
Sound turns off completely
Keyboard redirected all inputs (backspace = g and so forth)
My friend claims it's because I OC'd my pc, but I'm running an E8500 at 3.86 which is a relatively mild overclock, plus repeated OCCT/Prime tests show my system as stable when running for 2+ hrs.