There are a number of spyware removal programs available that will clean up the cookies, registry entries, and other files that some web sites and programs that you download install to allow a web site to track your internet usage (or other malicious functions). The spyware removal programs attempt to clean up these entries so that your computer will not be reporting your usage to these sites. You need to be very careful when using such programs as they can sometimes damage your system, in some instances to the point where you need to reinstall Windows. The following is an example (note that this type of thing could happen with any spyware removal software so you need to be careful when selecting what entries to accept).
I recently downloaded a free program called Spybot Search and Destroy to use it to clean up the entries on my computer as the spyware removal program that I had been using (AdAware) had stopped providing signature file updates while they concentrate on the new version of their program.
Unfortunately with the latest version of Spybot's signature file installed, the program reported spyware software called CDilla as being installed on the computer. When I selected to clean up this spyware it resulted in the removal of the Windows system.ini file which required that I reinstall Windows in order to recover my system.
Fortunately, I had a copy of the Windows CD along with a copy of all of the service packs and patches on my hard drive so that I could reinstall them all from there and was able to use Belarc Advisor to check which service packs and patches were corrupted by the Windows reinstall and therefore needed to be reinstalled from my backup copies.
I have more recently received an email from Spybot advising that this problem was caused by my having downloaded the 'Includes' (detections) update but not the 'Main Application' update. This means that the problem I describe above would not occur when you use a version of Spybot with a signature file intended for that version. Unfortunately the program did not check that a new signature file was intended to be used with that version of the program. I have been advised that this problem has been fixed in version 1.2.
I suggest that if you do decide to use one of these programs that you examine each entry very carefully to ensure that the entries that you are deleting actually are spyware and that you are not causing more problems for yourself by removing what has been identified as spyware. When you know that you have particular spyware installed on your system, one of these programs may provide the easiest way to remove it but you may want to consider limiting what you allow the spyware program to remove to that specific spyware.
This article written by Stephen Chapman, Felgall Pty Ltd.