Adding the addresses to the WebAV trusted sites didn't work for me either. I found that pinging www.msftncsi.com from command line usually clears the exclamation mark on the icon. I seem to have been able to clear it permanently by adding http://www.msftncsi.com to the Trusted Sites in Internet Explorer. I've left the sites as trusted in WebAV as well. No idea why it's needed in IE, but it has worked on two machines, so far.