take the side panel off make sure
your fan is in working order
if fan is NOT working then you could have fryed your harddrive
this will make your pc shut off ..
i just had same thing happen to me lost all my pixs ect
IF you do buy a new pc BUY a back up externial drive trust me for $80.00
or less it will save you headaches ask a qualitifed sales person about this a Tech!