I just reproduced it now. I just went to "System > Preferences > CompizConfig Settings Manager", I then scrolled down and clicked the box to enable the ringswitcher. Then I just kept hitting the hotkey to use it (window+tab) over and over again. It took about three tries before I got the same results, a black screen with a __ sign blinking, then it took me back to my desktop for a brief second, then to the login page.
I just reproduced it now. I just went to "System > Preferences > CompizConfig Settings Manager", I then scrolled down and clicked the box to enable the ringswitcher. Then I just kept hitting the hotkey to use it (window+tab) over and over again. It took about three tries before I got the same results, a black screen with a __ sign blinking, then it took me back to my desktop for a brief second, then to the login page.