Fish swim, birds fly and software crashes. The program that never chokes has yet to be written. If your screen suffers the dreaded freeze, though, you might be able to escape by keeping your cool and pressing the right keys.
Take a break and get a cup of coffee. Sometimes a program that seems irrevocably frozen is just temporarily stalled.
Once you're convinced that the program really is stuck, it's time to attempt a graceful exit. On a Windows PC, press Ctrl+Alt+Delete. In addition, if you're running Windows NT or 2000, click on Task Manager. On a Macintosh, press Command- Option-Escape.
In Windows, select the program you want to quit from the Close Program dialog box or Application list box. The program will probably display the words "Not Responding." Choose End Task. On a Mac, click on the Force Quit button in the dialog box.
After the program shuts down, save your work in any other open applications, restart your computer, then restart the program.
If you can't shut down the program, use the computer's reset button, if it has one. Laptop owners should consult their manuals for finding the reset "paperclip" hole.
Unplugging the computer from its power source should be only a last resort. It's like stopping your car by driving into a wall. Be careful with Ctrl+Alt+ Delete. If you press it twice in succession, your computer will restart without asking you to save your work.