Pc Stability Test I Need Help - My Monitor Turns Itself Off (or Graphics Card Malfunctioning?)?

I need help - my monitor turns itself off (or graphics card malfunctioning?)? - pc stability test

First, it is said that this usually happens when I play World of Warcraft (I know, I'm addicted: P). What usually happens is that the screen freezes, and can the last 5 minutes, during which the mouse can move freely but can not ALT + TAB, ALT + F4, Ctrl + Alt + Del or something. Frozen after 5 minutes the screen on my screen goes black and I have to manually restart my computer.
It happened once when I have a Windows message appears frozen screen and said: "The screen nv4_disp has ceased to function normally. Save your work and restart the restore full display functionality. ..."

He joined the overheating problems because I work with my PC-side bar, if eliminated, may not like the overheating.
Should be With a little technical advice on the WoW forums, I downloaded a program called nTune (a monitoring device on NVIDIA hardware) and I found a "stability test, the last 10 minutes - and I have the same kind the injury in the game after just 3 minutesutes. I see no problem (of course), I see only a black screen.


This is very, very, very, I repeat, be very frustrating, any help / ideas / suggestions on this would be appreciated oh so much!
It is not too obvious, since my PC back from a technician than a week, and if lost, must be something very subtle ...