A new and kind of really annoying behavior in the Guild Wars 2 64-bit client has started cropping up ever since the last build was released and installed on my machine. Occasionally the game will lag a little bit and then the whole game window will turn black. I can see and move the in-game mouse cursor. The in-game music still plays also. Other applications continue to display normally, so I doubt it’s a video driver crash. People have told me that in-game I appear to log-off at this point.