I have an Asus laptop running Ubuntu 12.04. It's configured to do nothing when the laptop screen is closed. But sometimes, when I close the screen and when I reopen it, after I move the mouse to reactivate the screen, my Unity interface is frozen and I can't click on anything. I can move the cursor, and if there's a music playing it keeps playing, but I can't click on anything. I can open a bash shell typing Ctrl+Alt+F2, but there I don't know what to do, I can only login and type sudo reboot to reboot the machine... Is there someone that has the same problem or that knows the solution?