'Stop' errors can be caused by a number of things, Pyroxide, both hardware and software problems can cause them, so they are usually hard to pin down quickly. Try removing all your peripherals and unnecessary cards and run a skeleton build see if it cures the problem. If it does cure the problem re-install your hardware one by one. A faulty memory module can be a prime suspect, so if you have more than one module installed, remove some and run on one module, interchanging it with another module if all is well, to try and eliminate it as the problem. You could run a test on your memory with "Memtest86" click here see if it reports a problem.
You haven't said which version of Windows you're using, so let us know in your next post, but try some of the above first.