Hi
the solution is so simple that i slapped myself for not doing it sooner because I too was having this issue.
In the group or sitewide setup page, you have to first install sitewide and then once you have that done, install group forums.
This creates a file that bbpress needs and everything works honky dory after that.
If you don’t want groups to have discussion forums, then simply disable that feature. This can be done per group or to all.
here is a screenshot
http://s15.postimage.org/8vc557n3t/Untitled_1.gif
as you can see the forum tab does not show as being active