Re: Cookie Hell: WPMU + BBPress = bloodshot eye balls
It will still let different cookies if you don’t have them ‘integrated’ for the login from the config.php. That is why I was leading you towards those articles. I am sure being an WPMU user you are fully aware of working with complex issues and I didn’t want to try and ‘dumb it down’ too much. In terms of the cookies issue, I have had plenty of problems moving things around and changing structures to know that the ‘WordPress Integration’ under the bbPress Documentation is the best when bbPress is in a directory inside WordPress, but not always!
If you let me know how you have it setup and what you have in your wp-config.php and config.php for cookie and integration stuff, I might be able to assist more. I just know that if you already installed bbPress and it is using bb_users versus wp_users, it might be harder to get the cookies working (at least in my experience)..