Also when you try to logout from adminbar using ie8, it won’t work! You are still log in no matter how many time you try to log out from admin bar. Please help?
I think the reason you haven’t gotten a response here is that people are having trouble understanding what you are talking about. Are you using wpmu 2.7.1 as well as bp RC2? wpmu 2.7.1 is required.
OK, I found the problem, but I don’t have a solution, if you look at https://codex.wordpress.org/Upgrading_WPMU and this is upgrading for 2.7 to 2.7.1 but the process is the same with 2.6 to 2.7.
You see:
define(‘ADMIN_COOKIE_PATH’, ‘/’);
define(‘COOKIE_DOMAIN’, ”);
define(‘COOKIEPATH’, ”);
define(‘SITECOOKIEPATH’, ”);
If I add that into wp-config.php as instruct, when a user log in and then use the log out link from wp-admin or on the adminbar, they are log out from wp-admin but not really log out from buddypress member or home theme or adminbar at all. Though if you log out from buddypress member or home theme directly, you are log out of everything, but adminbar still is a problem as when you click log out it only refresh.
Hope that clear the fog up. So when I remove those lines above from wp-config.php, everything works just fine.
How to fix?
If removing those lines fixes the problem for you, I would say remove those lines.
Those are settings that need to be modified to correctly for your particular install. WordPress and bbPress will often times suggest those settings for you, but it may not have gotten them correct.
I think I understand what you’re saying, and honestly it doesn’t resonate in my mind how this could happen unless your cookie settings are mucked up. WordPress and BuddyPress use the same login and logout functions, they are performing the exact same tasks.
Try deleting all of the cookies for your particular site, and try logging in/out again.
Have you attempted to integrate bbPress or have you modified your cookie settings in any way?
Removing fix, but don’t u need these lines at all? I had attempted to integrate bbPress before, but it wasn’t working, so I remove bbPress altogether. Is this why this is a problem? How to fix?
WordPress and bbPress use several cookies to ensure your identity across all directories and areas that are important to the applications. When those cookies are out of alignment, things start working strangely like you describe.
The best thing is to check the cookies that your site is dropping, review the information inside them (typically with Firefox) and see if there are any places that are obviously incorrect or pointing to the wrong locations. Then, you use those global variables to adjust the settings back into place.
This is one of those bugs that’s difficult to diagnose, difficult to direct you to a fix, and hard to explain where to even start.
It’s also PIVOTAL that all of your separate applications (WPMU, BP, bbP) are all correctly installed/upgraded to begin with. If you’ve never gotten to a point where they were playing nice together in the first place, it will be extremely hard to figure out what’s wrong.
I agree with JJJ – If removing those lines fixes it, leave it as is. But if you\’re still unhappy with the way something is working, you could try my integration tutorial.
I\’m assuming there\’s nothing important in your bbPress database yet since you said you wiped it all out and tried again. If this assumption is correct, start with a clean install of bbPress by deleting the forums/bb-config.php file. Also, drop the tables in your database that start with bb_
You can find the tutorial at http://theeasybutton.com/blog/2009/04/30/integrating-buddypress-10-wpmu-and-bbpress/
It was written for BuddyPress 1.0 but works exactly the same for RC2.
Good luck and if you fix it, please remember to let us know so we\’re not still trying to find a better answer for you. 
Arghagain-
Adding to what jjj and TheEasyButton are saying, if you are still having issues then it is important to start from scratch. You must get WPMU functioning properly before installing BuddyPress. Then make sure BuddyPress is functioning properly before installing and integrating bbPress.
From what you are saying, it is not clear if you are upgrading WPMU from 2.6 or 2.7? Did you already have a working copy of WPMU installed? If so, what version?
If you are upgrading from 2.7 to 2.7.1 following these upgrading instructions, then make sure you finish the upgrading process by logging into WPMU’s backend as site admin and going to “Site Admin -> Upgrade”. Also, make sure you use the wp-config-sample.php file that comes with WPMU 2.7.1 and modify that version as needed. Do not use an older version of the wp-config.php file.
If you do not have an active site with real members and you are only in testing mode, then you can safely delete everything and perform a clean install. This means that you do not have any data in the MySQL DB that is worth saving.
If that is the case,save to a separate file any custom themes you may have created or installed. Also, save any 3rd-party plugins you may have installed for WPMU. Then, start from scratch. Delete everything including your MySQL DB. Once you have reinstalled WPMU succesfully, you can copy back your custom themes and 3rd-party plugins into their proper locations.
Finally, if you are still using BP RC2, it is time to switch to BuddyPress 1.0, the public release version of BP.
Arghagain-
You’ve marked your thread as resolved. Would you please share with us what actions resolved your issue?
I didn’t notice status changed to resolve, but it’s not. It’s somewhat resolved because I remove those lines.
I have a perfect working WPMU 2.7.1, and all I want to do is to add those lines as wordpress mu’s tutorial site suggests for security reason. I don’t need BBPress. I had tried installed BBPress before when I first installed BuddyPress. I didn’t get BBPress worked with BuddyPress so I ditched BBPress.
Clearly I have a working WPMU 2.7.1, and working BuddyPress 1.0 (final). Though my only problem is by adding those lines, the logout link won’t work properly. It’s obvious it has to do with cookies and sessions.
So by removing those lines meaning I’m not doing exactly like WordPress MU tutorial suggests. So it’s not resolved. I wonder because what I did with BBPress before and then decided not to use BBPress by removing it has an after effect that affects my situation now? I remember that BBPress requires you to mess around with cookies and stuffs like that.
Unless things have changed and I’m way behind on the new version, you need bbPress in order to use BuddyPress to its full potential. bbPress is what makes the groups work.
I had lots of login and logout issues. And to fix them, I had to “mess around with cookies and stuff like that.”
1 thing was that I copied all of the auth keys from the wp-config and put them into bb-config. Another modification was that I had to define the cookiehash. When logging into bbPress, I didn’t have that hash so there were 2 separate cookies being created. 2 separate cookies means that logging out of 1 side doesn’t kick you out of the other.
Ya BBPress makes u mess with cookies and I didn’t like it. I have a hard time to make it work, but removing BBPress, the BuddyPress is still working fine. BBPress is only a module, and so it shouldn’t affect the whole BuddyPress.
This is a wpmu/bbpress integration issue not a bp issue as far as I can tell. Since this is not a bp support issue, marking the thread as such.
