Unfortunately, this is a normal part of computing in today's world.  You may or may not know what has caused the problem.  But in the end, it is the way that you handle the problem that will make all the difference. 

Look for the obvious  

First be patient.  If your computer fails to respond to your keystrokes, it may have a problem.  However, the computer could also be busy performing some function that you may not be aware of.  For instance, your computer may seem to stop when automatically saving a file or when printing something in the background.  So give it a minute or two.  If it still doesn't respond, look for an obvious problem first.  It may sound simplistic, but sometimes the problem is easily found.  If your screen is blank, check the power cable.  Check to make sure that the power to the house has not gone off.  Also, many newer computers have a suspend feature that blanks out the screen in order to save electricity.  Press a few keys to see if the computer will come back to life on its own. 

If your screen is still on, but your mouse clicks and keystrokes don't elicit any response, again, check the obvious first.  Make sure that everything is still connected.  Perhaps your dog just ran out from under your desk and he or she loosened the keyboard cable or the mouse cable. In many programs, the Escape key, which is marked Esc, will take you back one step.  So always try hitting the Escape key a few times before you concede that the computer is truly locked up.  If you still get no response and the connections check out okay, it's time to go on to the next step. 

The magic key combination

The next step is the magic key combination.  Find the keys marked Ctrl, Alt and Del.  Press these three keys all at once. This key combination is a remnant of the DOS days of computing.  In DOS, pressing these three keys caused the computer to restart or "warm" boot.  The Windows operating system uses these three keys in a similar, but slightly different way.  With the introduction of Windows 3.1,  this magic key combination, checked each application and gave the user several action choices.  

Luckily, when Windows 95/98 was introduced, it was better at isolating problems than the older versions of Windows.  When you hit the same magic key combination in Windows 95/98, you were presented with a list of the programs that were currently running.  If Windows found the offending program, it will listed the words "not responding" next to the programs name.  You could highlight the name of the errant program, press End Task and return to your computing. 

Windows Me, XP, and Vista made the Ctrl+Alt+Del combination even more useful. When you use this combination in Me or XP, you are shown a list of running applications in a box called the Windows Task Manager (on the Application tab). You can close any application that are running from this box. You can even close applications that have hung, which are usually marked "not responding".

Occasionally, even the Close Program Box and the Task Manager freeze.  If this happens, your last resort is to restart the computer.  If your computer has a restart button, you can press it to restart the computer.  If you don't have a reset button, turn off the computer.  Wait several minutes, then turn it on again.  Unfortunately, closing any program like this or turning the computer off will result in your losing the changes that you made to the document that your were working on since you last saved it.

 Losing data 

It seems that all computer users learn this lesson the hard way.  You must save your work often, just in case something goes wrong.  You will find that some programs have an AutoSave feature.  For instance, if you were working in Word when you were forced to restart your computer, when you turn your computer back on you may see that Word has restarted your document with the label "Recovered".  If this happens, you should express your gratitude and immediately name and save the document yourself.  While the AutoSave feature can come in handy, don't rely on it.  It is always best to save each document yourself as often as you can. 

Repairing your hard disk 

If you turn the computer off without exiting Windows properly, certain files on your hard disk can be left open or can be damaged. If your computer freezes more than a few times a day, you many have a wayward program or a hardware problem, but if this happens only occasionally, don't worry about it.  It really does happen to everyone.