En6800gt problem While playing any games such as need for speed: most wanted, call of duty 2 after a few minutes the game will exit and return to the windows screen. When it returns to the windows screen, its as if there is no graphics card installed showing minimum resolution that cannot be changed in the display settings. The graphics card isnt over heating or anything, its annoying the heck out of me trying to fix it. Can you help me?

Weird dood, I just took one of these apart 2 hours ago. the way its designed, the heatsink gets very clogged and will cause the card to overheat. I know you said it aint overheating but are you sure? It sounds like that is the exact problem.
Take off the cover of the heat sink (you will need an ity bity screw driver), if you see giant dust bunnies trapped in there your card is probably overheating. Mine was anyway.
The "heat pipe" they have for a sink is a total joke here. buy a new heatsink that is open air. not a pipe. or just keep cleaning it every month.
hope this helps. BTW get rivatuner to monitor temps, it will create a log so you can see temps while you game and even when it resets!

Did you try reinstalling the graphics driver? Try to update to the latest driver. if you have an overclocking tweak, disable the tweak and try.