I am trying to uninstall old anti-virus program so I can install a new one I have downloaded but when I went into the Control Panel & clicked on "Add or Remove Programs" it did not come up with the list of programs. I closed it & tried again but now I can't even get into the "Add or Remove Programs" window from the Control Panel, I click on it but nothing happens. Can I still install the new anti-virus program without uninstalling the other one first?