Whenever i try to exit from full screen on youtube or any other site my computer freezes and i have shut down by pressing power button. After pressing esc or double click, mouse icon can move but nothing is responding even ctrl-shift-esc . I waited 20 minutes once but didnt worked. It happens so often and very annoying anymore please help...

Whenever i try to exit from full screen on youtube or any other site my computer freezes and i have shut down by pressing power button. After pressing esc or double click, mouse icon can move but nothing is responding even ctrl-shift-esc . I waited 20 minutes once but didnt worked. It happens so often and very annoying anymore please help...