black screen nvlddmkm

hello everyone

first i have read many pages and this black screen nvlddmkm crash is doing my head in

using
vista 64 sp2

problem started about 2 weeks ago, once while i was gaming, never throught much about it, now get when i am in gaming mode when i goto save something, BUT not all the time...i build things on a game called Trackmania, maniaplanet now, when i click the save button it hangs then a black screen and the messege says display driver as crashed and as recovered "nvlddmkm" note i have never got the blue screen of death

i have downloaded the newest drivers, i never download beta drivers
even people are saying i need a new graphic card, if thats true i would like info first and help from you's

the only thing i have changed is to go onto a moblie dongal for the internet, as i am living away from home right now, can not see this been a problem ?

please do not send me to a page with aload of problems i really need a fix
thx