It's video graphic driver failing that causes it. Currently with this latest update, there seem to be a bug in their coding that causes GPU to overheat dramatically. Mine goes up to 83 celcius and then my video driver report failing and i have to force close the game. It made me worry so i went to test my video card temps playing other games and it's normal 50ish celcius. So the only explaination is that it's DDO latest patch that created this issue. It was completely fine yesterday.
Check your GPU temps when you get into DDO, personally mine goes up at almost max even during the initial loading screen. So until they do another update, it's unplayable for me at least.
edit : Also shows my GPU load at 99% when in game.
Nvidia gtx 780 ti for reference.