Vista - Windows Security Center

recently something attacked my NAV (I am running Vista Hoem premium) and I
had to remove it and re-install it (successfully). Now my Windows Security
Center keeps telling me that the computer cannot find any anti-virus software
on the computer. I know that NAV is working, as I am able to get my Live
Updates, conduct scans and the program is lisetd in my Programs (and the
security shield is on my toolbar). Any suggestions on how to convice the
Security Center that I have NAV installed properly? FYI - this happens even
after I re-boot with the NAV on.
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Many thanks - Chuckrodent