I'm using Ubuntu 11.10 according to my help. When I press alt-tab, the display flashes a bit and then all my windows have no title bar. Without a title bar at the top, I can't even restart. All I can do is turn off the power. I had a terminal window open during one of these alt-tab presses, and I'm unable to type in the terminal window. This was working until today when I was asked to install some upgrade.
Please don't advise me to not press alt-tab. I'm have difficulty not pressing alt-tab due to habit and I'm not getting my work done when I have to powerdown a couple of times every hour.
This case happens in situation where u hold the alt key for a while (say 2 to 3 secs) and press the tab button, then monitor flashes implies unity breakdowns and move all the applications to single workspace, if you repeat it second time , you will end up with un accessible desktop where all applications hang.
Then you have only one option restart unity (ctrl + alt + f1) login enter unity command and enter (ctrl + alt f7)
U will get back your desktop but you have to arrange all the applications in the respective workspaces, which makes my day very very bad, I have switched back to linux mint which is at least stable
Sorry for editing it, I din,t find how to answer your post