If you’ve just installed new antivirus software, but Windows Security Center says you have no antivirus software installed, don’t be alarmed: It more than likely has installed properly and it probably is working. It’s probably that Windows Security Center can’t see it; that’s all.

If Windows doesn’t detect it and/or the program doesn’t tell Windows that it’s installed then Windows thinks there’s no antivirus software installed and reports to you that there isn’t any installed; simple as that.

Can you make Windows see it? Not really, no; but you can tell Windows that you do have antivirus software installed that it can’t see, and that you know it’s there and will keep a check on it so that Windows doesn’t have to.

Depending upon whether you’re running Vista or XP, there are different ways of doing this:

If you’re running Vista go to Control Panel and click on Security Center.

Click "Check settings" with regard to the "Malware protection" line.

This might not be exactly what your screen looks like; but in any event click the button marked "Turn on".

Once again this might not be exactly the same as the screen that you get. In any event click on "I have an antivirus program that I’ll monitor myself".

Malware protection changes from red to yellow and the state changes to "Not Monitored".

Now Windows Vista will stop nagging you. Ensure that you monitor your new antivirus program yourself.

In Windows XP go to the Control Panel and click on Security Center. The process is similar but a lot less hassle: Click on "Virus protection" and click on "I have an antivirus program that I’ll monitor myself".

Again Windows XP will stop nagging you; but you must ensure that you monitor the state of your new antivirus program yourself.