I just got Guild Wars, but after about ten seconds the game locks up completely and I had to reset my computer with the reset button. Windows XP didn't like that

Anyway, I have had similar problems with other games. But on a whim I quickly chaned Guild Wars to windowed mode, and it runs with no problems. Then I change to fullscreen again, and it locks up after a few seconds. I guess this isn't Guild Wars' fault since it happens with some other games as well (but not all), but I figure it's an issue with my graphics card. But I have no idea what exactly is wrong.

Does anyone have any ideas why this is occuring? Please help, I want to play in full screen!

-Zorax-