In beginning of December, I too, I had a problem with this virus called Win Security Antivirus 2012. I wouldn't click on install at all because it looked very fishy.It also took over the adobe flash player update. It took over everything and was not able to open any program or the internet. McAfee was supposed to fix this yet it seems like it couldn't do it right. Mcafee detected the virus and blocked it but the virus was still there. It was as though Mcafee was a bit too late. I did not even download anything from that virus which kept prompting me to click yes to install. I had to do another full scan with Mcafee and it detected more infected files and it quarantined them.
I also ran a malwarebytes scan and it found some more infected files that it deleted. Now my windows firewall is completely gone and I am getting same messages like the other people above. My Mcafee can't turn on the anti-virus. There is like no help out there. Mcafee should be able to help with this since they are the ones invloved with viruses and stopping them.
That antivirus 2012 was a nasty one and I am surprised that I see Mcafee and ISP providers, which some do provide technical assistance by the way, don't want to help yet it looks like a rampant problem especially in the month of December 2011.
There should be a fix with a click of a button to put back my firewall.