In the last two days I've been getting the message that there is no firewall turned on and when I click in the balloon it takes me to Windows Security Centre which shows the Firewall as being turned on. I have logged on as I have usually done before so there had been no changes to what I had been doing.

Below is the message in the balloon:

"your computer might be at risk

no firewall is turned on

Click balloon to fix this problem"

I'm concerned as I had previously never been getting this and the windows security center settings - showing the firewall as on are still the same from what I can see.

Is this something that anyone else has encountered and if so what should I do in order to further ensure that the firewall is working ok.