Where playing earlier today and was changing the display from fullscreen to windowed, and well it did not go well.
The widow gave me the message in the top left close to the WoW logo “Not Answering”
Then a popup message appeared saying “unable to start up 3D acceleration” or something close to that, and could only click “OK” and then game closed.
I started the game again and it was back in fullscreen, I tried to see if it was a 1-time thing, so I tried it again, but well… again it happened.