Game bug, or monitor bug?

So one day I had been playing guildwars for about 3 hours. I was busy capping skills to get my leet skill title. I decided to do abbadons mouth and the game went crazy on me when I got to the first boss i needed to cap. I could not see or hear anything from the game. I could alt+tab out of it but when i maxed it again, i still couldnt see/hear anything. I closed the game, got a little pissed and thought "OK may just be a random bug." I then tried the mission again and crashed AGAIN in the same way. I waited a few hours because I got tired of doing it. Later I was sure that this time nothing was going to go wrong... It crashed A THIRD TIME! It only crashes on THIS mission in a random area.

The third time I did it I noticed something, I had been targeting the monk boss and the EXACT SECOND light of dwayna finished casting, it screwed up (maybe it had something to do with it?).

Does anyone have any clue what the hell this is and why its doing it?

If you can alt+tab out of it, then its definitely a game bug. since it seems to happen in the same place/mission, maybe that part of the game file is corrupt? I would recommend uninstalling GW completely (delete the folder in Program Files after uninstall), then reinstall it.

Do that if you can't find a solution in a while tho, since its annoying downloading+decompressing every file again.

something I should have added: I could alt+tab only 2 out of the 3 times. The 3rd time, i had to reboot.