Alt-Tab Forces Me to Reboot

view full story

http://askubuntu.com – 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 (HowTos)