I did not see anyone else posting this issue, so here goes...
From my work machine ITunes, IE and Firefox access premium content ok. Popup asks for ID and Password. I supply it and off we go.
My home machine running the same versions (no firewall/no popup blockers) does not display the user ID/Password dialog box. I gets "401 Authorization Required" on IE and ITunes immediately.
It works ok with Firefox (popup dialog). I can log into the site with IE (apparently because the site seems to know who I am) and browse forums but can't read premium content with IE. IE won't let me access the http://www.manager-tools.com/registered-members/rss.xml feed for ITunes nor will ITunes, Firefox will.
I prefer to use ITunes on my home machine because that is where I listen most often.
Other than this annoyance, love the site. Thanks for all you guys do!