Be very careful, stand up
VERY slowly. Make your way outside being careful not to make
ANY sudden movements. Walk down your street to the nearest payphone and pray that no one goes near your
PC whilst you are away. Dial 911 and ask for the bomb squad, tell them that Al Qaida have been messing with your
PC whilst you have been asleep and that your computer is going to explode.
Or maybe you could just take it down to a computer repair shop. They'll tell you that your fan is either catching on something or the bearings have disintegrated and you need a new fan.
I prefer the first story but its more likely to be the second.