There's not much more frustrating than a program that stops responding. There are many things that can cause this to happen, such as hardware or software conflicts. When this happens, it is not always best to turn off the computer right away (which could result in data loss). In most cases, when a program stops responding to keyboard or mouse input, you can still get out and restart the computer properly by pressing the CTRL, ALT and DEL keys simultaneously.
Pressing these keys will bring up a window called Task Manager in XP and in Vista will open a screen that gives several options (Shut Down, Switch User, Lock PC, Task Manager, etc) and for the sake of this tip you'll want to choose Task Manager. From here you will see the programs that are opened. Beside the program that's locked up it will say "Not Responding." Highlight that program and click the "End Task" button. During this process you'll often need to be patient, because it often takes some time before the program goes away. It also may be necessary to go through this process several times before it goes away.
Once the offending program is closed, you should restart the computer to get a clean start before returning to the program. Often you'll find just restarting the program doesn't get rid of the problem, but rebooting clears up many problems that are still in memory.
Frequent lock-ups could indicate a serious problem, such as a corrupted file, or a hardware problem that should be addressed.
