It's Easy and Simple.
i. First Press "Ctrl + Shift + Esc" button same time in your keyboard. It Will Open "TASK MANAGER".
ii. You Can See Here Your Non Responsive Program in Application Tab.
iii. Just Select Your Program and Press "End Task" Button Below.
iv. If You are Prompt Just Press "End Now" Button.
Some times you should have to press "End Now" several times. {Windows XP, Seven}
v. In Windows 8 You Will Find "Process" tab Just like this :-
vi. After Selecting the Program Just Press "End Task" below, That's All.
Thank You.