[Paul den Hertog]

My only fix was to run bbpress 1.0-Alpha-6. Please read the most important topic in this forum @ https://buddypress.org/forums/topic.php?id=471 (about installing buddypress and integrating bbpress).

Read the first post, you’ll find that everything you need to know is there

Also http://bavatuesdays.com/integrating-wpmu-buddypress-and-bbpress/ is an excellent tutorial.