When users are not logged in to portal, but try to navigate to groups, they are just presented with the never ending spinner.

Other links either present the user with a log in screen or some other screen but Groups just sits there.

Is there a setting we have missed that will send this to the login page or some other display?
Update to above: we have recently upgraded the development portal to 10.8.1 and we don't get the same issue as the production server on 10.7.1