computer wont boot, fan runs hard, and there is 2 beeps that repeat over and over.
 

I was using my Dell Computer that is about 3 years old yesterday. I walked away and when I came back I Pushed enter to wake the computer up and the fan starting running hard and loud. Then it was followed by 2 short beeps then paused then 2 beeps over and over. The computer would not boot up and...