Earlier today i was playing a game with a couple of friends when suddenly these little white squares appeared on my monitor in an almost gridlike fashion. The game froze and so did my screen, but quickly came back after a short while. Since then every time i open a game or do anything even semi-graphically intensive, the same problem is occuring, sometimes even crashing my computer. Im running a MSI GTX 580 Lightning and have been without problems for almost 2 years now. I also tried running the OCCT 3D GPU test and the same problem occured about 40 seconds in and crashed the program. Some help or replies would be greatly appreciated