This kept happening to me a while back when I owned an e-machines PC. After
I owned it for a year all of the sudden it started to do this, I cleaned the
insides real good, (Dust on fans) and even used some type of gel that was
recommened for the CPU (something to do with heat). It worked for while
then about a month later started to do the same thing again. Tried all of
the above all over again and nothing. I ended up getting an HP PC and after
1 1/2 years, guess what, the same thing. This time I used that gel on the
CPU, snugged the heatsink nice and tight, cleaned all the fans and it is now
working great.