When a game crashes, I get a grey screen with just a mouse

I get occasional crashes with the game Guild Wars 2 because it can't render an in-game web browser. Sometimes when it crashes, the screen goes completely grey with just the (movable) mouse showing. After a while, it just returns to the login screen and everything acts like I restarted the computer. As a note, my uptime (found by running uptime in Terminal) is still 7 days, so it didn't actually fully restart.

I figure this is my graphics card restarting, but I was wondering if anyone else can shed some light on it. Thanks!