0x0000007f?

[Gary66]

Hello
Windows Vista Home Premium Service Pack 2 (build 6002)
Board: ASUSTeK Computer INC. Maximus Formula Rev 1.xx
Processor. 3.00 gigahertz Intel Core2 Duo.
Slot 'DIMM0' has 1024 MB
Slot 'DIMM1' has 1024 MB
Slot 'DIMM2' has 1024 MB
Slot 'DIMM3' has 1024 MB
NVIDIA GeForce GTX 280 [Display adapter]
power adapter. 1100watts
HP 2159 [Monitor] (21.7"vis, s/n CZQ91403BW, April 2009)

I have been having problems lately since i updated a driver to play arma II, with random crashes whilst playing empire total war. Its mainly when in battle the game plays fine then i get a reall framerate problem that seems to come and go then but seems to get worse be a full ctd. the worst case being i get a bluescreen when i try to reboot though this has only happened twice. (0x0000007f) The first time it happend it said something about bad ram or something so i did a memory diagnostig test and it found bad ram, i have, since then i have replaced the ram and tested ok. but i still get ctds sometimes and i have changed my vga drivers a number of times, so i am at a loss as to what to do.