could be a number of things.. if your computer is over heating try leaving the side off your case.. could be the air flow of the fans.. air flow is everything with over heating... your power supply should be the only fan blowing air in, while the rest suck air out.
it could also be a problem with updated software for your computer.. if something isn't up to date or is isn't properly installed, it could freeze your computer when it tries to access the programs.. also software will fuck up its own installation some times.
use the help section next time
/moved