PC Randomly Freezes

[Aaron-kun]

My PC will randomly freeze every once in a while when I'm playing a game.  It's happened a few times in the last week or so, but the most recent was just a little bit ago.  I was playing FarCry 3 for about an hour, and it froze to the point of me having to reset my computer.

 

I scanned for viruses but came up with nothing.  I've been monitoring my PC temperatures through MSI Afterburner.  My CPU and GPU temperatures have stayed in the mid 60's to low 70's (70-72) while playing a game.  It's not an overheating issue, is it?  I've read that having a PC around 60-70 degrees is safe.  Is it not?

 

Is there anything else it could be?

[spartaman64]

hard drive maybe