Thanks for the info. I am thinking of a certain situation in Windows XP where
I had uninstalled avast from add/remove program. When I rebooted the system,
security center though an a/v was still installed, even though the avast program
folders were gone.
I had to run the avastclear in safemode for security center to reflect the true situation.
If I had some more time it might have been fun to find out what the security center was looking at
that made it believe an a/v was installed and active, when in fact only some remnants were there.
Presumably, something in the registry.