GW error-restarting

When I tried to enter the mission at Gate of Desolation(Nightfall) and when I tried TA, my computer just restarts... There isn't any warning or anything, it just loads the area, screen turns black and computer restarts. The only thing i tried so far is windows suggested turning down hardware acceleration, but when i did that GW just wouldn't run. I haven't tried any other missions, but I assume the problems will be the same. It did work for a while, but with no warning it doesn't work anymore. It didn't happen over the course of an update or anything, it just stopped working.