I'm running the Steam Edition of FSX. I submitted a ticket, and tried the recommended solution (disabling antivirus and Windows Firewall), but the same error still pops up. It happens very quickly, as if the installer is not even trying to connect to the server for authentication, rather than trying and timing out.
I purchased the Aeroplane Heaven B-17 yesterday. When I launch the installer and select my game type (FSX), the authentication step won't go through. I get a message saying that "Navigation to the webpage was canceled." I had disabled my antivirus and Windows Firewall, and I always run the launcher as an administrator.