I have disabled the global forum directory in the main settings. However, when you are in the group forums and reviewing a topic there are two buttons above the topic. One to return to the the group forum and one to go to the group forum directory.
I had wanted to have that not show up on the site as one, it seems to cause confusion for many users as it takes them to a page with topics and replies that don't pertain to their group. I would like to remove this button/link so it does not show up. The other issue is that I am setting up a site wide forum as well and having both causes even more confusion.
here is a link to a page which has the group forum directory button.