I installed the plugin following the instruction step by step, yet I faced the problem that had been metioned few times before i.e.: I could not log into the wp-admin panel.
Finaly I did it after i found that the session id disappears.
I don't how it looked in other cases in which the plugin casued the problem in accessing wp-admin but here it is what i found:
1. I perform a proper installation
2. I login in using sidebar widget 'phpBB Bridge Users' an I get redirected to phpBB login page and back again to WP site as a logged user
3. Now, in the sidebar panel I have several links, some of which directs to administration of phpbb and WP.
However, the seesion id is not sticked to links directed to wp-admin!
The links looks like these:
phpBB link: http://www.domain.com/forum/adm/index.php?sid=0e474...
WP link: http://www.domain.com/wp-admin/
So if you add the session id to the latter you instantly get the access to wp-admin:
The same situation with each and every single link in the admin menu - you need to apped session id manually to open any tab.
This is problably the only way you can easily diable the plugin (in a quite civilized way)
I wish it was helpful so developers could fix the bug.