Applications will freeze up from time to time. Usually there's an accompanying dialog box that tells you that the "Application is not responding" and that you can click "End now" to close the application with the risk of losing unsaved data.
Uncomplicated stuff. And sometimes this is necessary because you can't work in other applications or shut down your system in an orderly fashion until the frozen app is dismissed. It's bad enough to have one application crash; you want to minimize the damage as much as possible.
But sometimes the application just won't close, no matter how many times you click "End now." On other occasions, the applications just freezes, and you never see the "End now" dialog box. In these cases, you might have to open up the Windows Task Manager and close the application manually. To open the Task Manager, press Ctrl+Shift+Esc on the keyboard. (I recommend this shortcut over Ctrl+Alt+Del because the latter is the log on/off keyboard command for XP Professional machines connected to a domain.) Now, choose the offending application from the Applications tab and then choose End Task.
But sometimes even that does not work. Here's the failsafe: instead of killing the application, kill the process that's responsible for the application. The closest analogy to this I can think of is to turn off an engine by taking out the spark plug: the process is the spark that "ignites" the engine.
To do so:
The only caveat here is that you should be aware that closing a frozen application might close all instances of that application that you might have open. For example, you might have several Internet Explorer windows open, but just one is causing the problem. Closing the application will close all IE's windows, not just the one that is causing the problem. Unfortunately, there's nothing you can do about this.
But let me be clear: killing the process is a last resort. The preferred method of closing a frozen application is to use the Applications tab, not the Processes tab. Killing the wrong process can cause the entire system to crash.