I had this same problem for the longest time, I got so mad over it, it was the MOST ANNOYING THING IN THE WORLD until I fixed it. Tell us when it happens. You may or may not have the same problems as me, so most people will tell you to update the drivers. For some reason, when I removed two of my 4 ram sticks out of my system, it ran like a charm. for me, it was whenever I did something graphics intensive. then I fixed it and now I am very happy.