Task Manager

If you are stuck with an application that freezes and will not respond to anything, you can go to Task Manager to force it to close.
Press Control + Shift + Escape to open the Task Manager.
Then Arrow down to the problem application, Tab to the End Task button and press the Spacebar.
If all else fails when your computer is frozen, you can press and hold the power button to switch it off, but this is a last resort.