A computer that stops responding or freezes can be caused by many different problems. For example, a software or hardware conflict, lack of system resources, a bug, or other error in the software or drivers can cause a software program, Windows, or the computer to stop responding.
What to do when a program stops responding.
To recover, press the Ctrl + Alt + Del keys on your keyboard to open the Close Program or Task Manager window. Once open, highlight the program that is not responding and click the End Task button to terminate the program. If another window opens, click the End Task button again to confirm stopping that program.