Go to Start | Settings | Control Panel and double-click on "Security Center." If you click on "Anti Virus" there, if the system has not recognized your AV, there should be a place where you can click something like "I have an AntiVirus program installed and I cross my heart and hope to die I promise that I will manage keeping it up to date myself and I'll eat worms if I don't." This should turn off the flag at least until you've had time to let your AV be registered and recognized.
Once you've received Norton updates that recognize that you have the new updates, your Norton AV should automatically tell your Windows setup that it is installed, is running, and it will report the last time your definitions were updated. Once that happens you'll only get the Windows flag if you let your subscription expire or don't connect to get the AV signatures regularly.
(Note: If this just appeared, you may be a bit behind on updates(?))
If, as I suspect, you're suggesting that this may be the cause of Barbara's flashes mysterious flag, she can of course check the same place.
Some other perfectly good AV programs may fail to "register" their presence with the OS, so you may have to do it (as loosely described above) manually. With autoupdates, Norton will eventually take care of it - usually - under normal circumstances - if everything works - ...
Sometimes, a manual AV update (Norton "check for updates") will cause Norton to "discover" that you need the AV registration feature immediately, since in the manual process the update site should look at enough info about your machine to see that you should have it. That may speed up getting things in order.