[lmsalgado]

I was having the exact same problem, but with normal WP (not WPMU).

My problem was that I instaled wp and bbPress both in subfolders, like:

http://www.mysite.com/wordpress

http://www.mysite.com/bbpress

The problem was on cookies, since bbPress was creating them on root and wordpress both on root and on ./wordpress – but it seems that the ‘good cookie’ was the one on ./wordpress.

The ideal solution would be to set WP to use cookies only on root, but I wasn’t able to do it in a simple way. So I configured bbPress to set cookies on ./wordpress.

This was done by simply adding a line to bb-config.php:

$bb->cookiepath = ‘./wordpress’;

Now it seems that all is working fine.

Hope it helps you too