Before installing a new Antivirus you must uninstall every other Security Software which you have installed in your computer and then clean-up every part of them which might be remaining in your windows.
to do, first you must go to control panel and then “Add or Remove Programs” menu (for Windows XP) or “Programs and Features” (For Windows Vista / 7), in this window, find every program related to the current Antivirus vendor you are using (e.g. Main program, toolbar, update tool or…).
then, to cleanup left over, you need to run so called “removal tool” or “uninstall utility” by the vendor which you can find on their web-site, here is link of most common tools.
After using the tools to cleanup the old installed Antivirus, restart your computer one more time and then cleanup all temporary files, Click here to learn how to do it. now your Computer is ready to install the new Antivirus.
[box]If you have been unable to uninstall the product yourself and need assistant, visit the Support Center and open a new ticket regarding your problem, I will get back to you as soon as possible.[/box]