The problems you must face using an Antivirus are not always obvious. By not properly uninstalling an antivirus programs, you can experience system instabilities.
It is not unusual that you find problems when installing a new antivirus program due to traces of the older one.
The first choice you should use is the uninstaller that comes with the software. But if something happens on the process the following list can solve your problems:
Panda has created an uninstall program for every product, so select the proper one:
Panda Antivirus, Firewall 2007 Uninstall Utility
Panda Antivirus, Firewall 2008 Uninstall Utility
Panda Antivirus, Firewall 2009 Uninstall Utility
Panda Antivirus, Firewall 2010 Uninstall Utility
Removal Tool for Kaspersky Lab Products
This removal tool can uninstall all versions of Kaspersky Antivirus and Internet Security but under 64 bit operating systems versions 6 and 7 of the products.
For reasons that I don’t understand, Norton Antivirus leaves a lot of traces even if you uninstall it using the default uninstaller.
F-secure has created an extensive page about how to removal its antivirus:
Advanced F-Secure product removal
There is an uninstaller tool but F-secure only recommends it as a last resort.
Bitdefender Uninstall Tool
Avast Uninstall Utility
How to uninstall or reinstall supported McAfee consumer products using the McAfee Consumer Products Removal tool
Which program did we miss? Now you’ve removed your bloated AV software, check out the free Microsoft Security Essentials (MSE).