Since the last patch I can't alt-tab out of the game and back anymore without the screen visually freezing.
I can still click on things and hear the sounds that are supposed to play, so part of the client goes to e.g. my profile screen, but my display is frozen.
I also got an error.log and crash.dmp from last time when I used alt-f4 to close the client after it froze if that could help to identify the problem, can't find a way to attach them here tho. Tell me where I should send them if you want them