[anandasama]

You need to integrate the user meta and the cookie integration. Seems like you made a mistake with both?

Make sure you installed everything in this order:

1. Clean DB (No old WP_ or bb_ tables. Clean it)

2. Install WPMU

3. Install Buddypress

4. Install BbPress

I used this guide and got it working:

http://umwblogs.org/wiki/index.php/Integrating_WPMu%2C_BuddyPress%2C_and_bbPress