Re: WPMU 2.7 cookie integration
Dump all your cookies and cache. If you’re using Firefox, you can actually leave your cookies open while browsing, so with that open, log back into WP.
Make a note of your cookies.
Log in to BB. See if the cookies have the same name. You should have about 6 or so called wordpress_LONGSTRING and if you look at those cookies, the folder locations will be / or /forums or /blog etc etc. If they’re NOT the same cookie name, then you have missmatched AUTH keys in your forum.