Whole computer crashes loading into dungeon?

Hey, Something weird has been happening to me today. I log into the game, I'm on the Excalibur server and my character is in Mist, ward 2 I believe, but every time I queue up for a dungeon, soon as I start loading in my whole computer crashes and restarts itself.

The dungeon music plays but then freezes and starts skipping for a bit as the whole computer freezes up, then the screen goes black like the video card crashes, then it'll come back to a frozen stillshot of my computer with the completely black game window, then it just outright crashes, shuts down and starts up again on it's own.

The first time this happened I was trying to get into Amdapor Keep (non Hard mode) and the next times were for Lost City of Amdapor

any idea what's causing this?