Windows 7: full sceen app stops computer dead

I am using the latest video driver for NVIDIA 8600. (This is ASUS laptop G1S gaming machine, with 4GB RAM, duo processor and nvidia is 256MB....Windows 7 ult. with all current updates)
-- Every time I go into any full screen video, the sound sort of resonates at a low gutteral level, completely hanging the computer. Then it simply turns off my computer...not reset, but completely turns off the computer. This consistently happens every time ANY full screen a/v application... anybody have any idea what the hell is causing this???? My motherboard was changed recently (ASUS Head Office in Korea changed the board themselves). Now this problem appears but I can't speak Korean to interrogate them!!!

Run Malwarebytes full system scan in safe mode, if you have AVG uninstall it, and then use Driver Sweeper on your GPU and install the newest ones.

I did malwarebytes. I don't have avg; I use eset and ran clean scans. All my GPU versions are up to date. The problem still persists. I am trying to see if there is a motherboard problem..... Thanks for your help.

Issue resolved. Look...ASUS laptop motherboards have faulty electrolytic capacitors on motherboard....causes full screen a/v (hockey games, movies etc). The sound sort of echos, the whole computer hangs and then the computer abruptly shuts down. ASUS has to replace the motherboards. This issue has been confirmed with ASUS Korea.