As mentioned in THIS
[http://social.msdn.microsoft.com/Forums/en-US/45938ac5-5484-465b-8289-8352573dae0c/forums-release-with-nntp-bridge-october-29-2013?forum=announce]thread:
In order to get NNTP working properly, if you are a Bridge user please
go to "My settings" under "Quick access" and ensure that you have the
"Use NNTP Bridge" setting selected. In order to have the Bridge
authentication work correctly (even if you have this setting already
selected) all users will need to click the "Save changes" button. This
will ensure that the authentication credentials are
stored properly.
~~~Make sure you also have the updated version of the Bridge, this can
be found HERE [https://communitybridge.codeplex.com/releases/]~~~
Forums Program Manager