those can be caused by many things... i get them with my overclock to high. As brent said do that to the memory adn see if that fixes it. If not go to www.extremeoverclocking.com
and download prim95 and run it on test 2 for X hours (as long as you can) if there is an error on the machine it will fine it since it tests high memory and really stick it to it... 100% load on the machien so let it run while you are there and perhaps overnight since you wont be using it.
It is going to stress the cpu and push its heat to the max, if its prime stable for 12 hours or more.... the system is very stable.
If it goes to an error after only a bit.... something is up. You can then run Memtest86 to test the ram, it will tell you with if the memory is a problem.