To get bbpress login integrated with WPMU I had to add the following lines to config.php, after $bb->wp_xxx settings:

if ( isset( $bb->wp_table_prefix ) ){

$bb->usercookie = ‘wordpressuser’;

$bb->passcookie = ‘wordpresspass’;

}

Because WPMU does not use HASH in its COOKIES.

[@fel64 Member 17 years, 6 months ago]

Thanks for posting the solution, then