About a year ago faced a problem: at any random moment the GUI just stops responding to input devices. All applications continue to work, the messages in IM come pop-up Windows appear, interestingly, the cursor moves with the mouse, but nothing can be done. Sit there and watch.
A few months ago was solved by switching on a nearby Desk and back (Ctrl+Alt+right). Now even that does not help (though the problem began to meet much less frequently — once or twice a month). You have to open the console and restart gdm. In the same console restart hal and dbus — too anything.
Over the past year, I think, updated all that is possible: both xorgand gthumb (sometimes when it is closed and when working in the Gimp it happens), and the driver from nvidia, and several complete upgrades.
Like all. Faced?