Follow Up: More computer Trouble

[Jurollo]

I posted about a problem I was having after updating Windows about a week ago. Essentially the computer shut down and would get to the windows logo then would flash a blue screen and fail. after 30 minutes of trying to fix it it finally came back on. I thought it was solved, however, it has since started to do so again, after uninstalling all the updates and doing a system restore. While doing regular things the computer will just shut down and when i try to restart it I get STOP: c000021a as the fatal error code. Then after waiting a little while it starts again, I built this computer and never had issues for the first two months, I leave it on all the time so could this be a heating issue? Or is it something else? Any thoughts would be appreciated.
~Justin