Can not get rid of "Authentication Required"

Hi folks - Windows 7 newbie and first time poster here.

I turned on IIS and configured a web site with no problem. However, adding an FTP site always produces an "Authentication Required" window when testing. Tried multiple combinations including "Anonymous/Basic" turned OFF (not selected / not enabled).
"HomeGroup Connnections" is set to "Use user accounts and passwords to connect to other computers" - however, I also tried "Allow Windows to manage homegroup connections". I am using the Norton Security Suite as provided by Comcast but I do not see where it can be causing this problem because I temporarily turned it (the Norton Firewall) off and I still was prompted for the "Authentication Required".

Your solution is much appreciated. Thank you!

I have no idea myself but perhaps the configure & enable links in this Microsoft forums answer may give you some insight.