Johny.: Please check if they have different protocols in address bar - https and http - or are they the same? + when you refresh it stays the same in each tab?
I've done a bit of poking around at the error.
When the menu button disappeared I switched to https and that worked at first. But now it doesn't.
But hovering over people's avatars for the chat / wishlist menu doesn't work either, so I assume it's a (almost) complete failure to load angular.
In the console when I type angular that works, and angular.element() works, but if I try to get the injector from that to access services it fails. (just returns undefined)
That being said, I've never particularly tried to access services on the forum pages so I don't know whether that was always the case.
Hope that might help a bit :)