Windows XP is set up so that it can automatically connect to the Microsoft Updates site, download the latest patches for the various Microsoft programs that you are running and install them for you automatically. This can have benefits in that security holes are often discovered in any program (not just those from Microsoft) and having this option turned on means that, unlike earlier versions of Windows where most home users didn't install the patches necessary to ensure that their computer is secure, the patches are installed for them automatically. This should have the effect of making Windows XP a much more secure operating system.
Unfortunately there are times when Microsoft gets it wrong and the patches that get downloaded to fix one problem break something else. If the something that gets fixed is of no concern in your situation but the something else that got broken is critical to your computer usage this will be a real annoyance - particularly since even if you uninstall the patch manually the automatic update will automatically reinstall it.
Fortunately, Microsoft has provided a means for more knowledgable computer users to turn off the automatic update feature. To do this you simply go into "Control Panel" to the "Performance and Maintenance" section and then select the "System" tab where you will find an option allowing you to disable "Automatic Updates". (It is arranged slightly differently if you have Control Panel in Classic mode but you will still find the option under System). If you later decide to turn this option back on you just go back to the same place.
If you do turn this option off then you must remember to check manually for updates on a regular basis as otherwise you will be leaving your computer exposed to any security risks that are identified and fixed by the patches issued by Microsoft.
This article written by Stephen Chapman, Felgall Pty Ltd.