I am having this issue as well with the "SQL 2012 - General" forum (RSS). It does not seem to matter whether I am logged into SSC or not.

When not logged in I can still see the Forum on http://www.sqlservercentral.com/Forums/[/url] so none that theory doest not seem to fit either.

The "forum number is above 1000" sounded plausible, but I have no trouble with "SQL Server 2005 / SQL Server Newbies" which is RSS feed 1291.

I tried in Chrome and IE.

Any ideas on why this occurs, or guidance on how to resolve?