I've tried bridging coppermine with phpbb2 and I had trouble....
mainsite is http://www.fiestatime.amigadude.com
phpbb2 is http://forum.fiestatime.amigadude.com
coppermine is http://gallery.fiestatime.amigadude.com
all subdomains are hosted in the same directory
coppermine bridging is set to
Forum URL: http://forum.fiestatime.amigadude.com
Relative path to your BBS's config file: ../forum.fiestatime.amigadude.com/
Use post-based groups?: 0
Cookie prefix: phpbb2mysql
bridging with it setup like that had the login in coppermine redirects you to http://forum.fiestatime.amigadude.com/login.php to login. It didn't return you to coppermine after login and it hasn't logged into coppermine when I manually go to http://gallery.fiestatime.amigadude.com (haven't added a gallery link to the forum header yet)
I was kind of in a hurry so I just stuck it in a gallery directory on the forum subdomain and now it works fine with these settings:
Forum URL: http://forum.fiestatime.amigadude.com
Relative path to your BBS's config file: ../
Use post-based groups?: 0
Cookie prefix: phpbb2mysql
But and here's the actually question... should it work with the forum & coppermine on 2 seperate subdomains (forum.domain.com & gallery.domain.com) or would 1 of them have to be on the domain (domain.com/forum&gallery.domain.com or forum.domain.com&domain.com/gallery)
and.... I've solved it myself.... You want to leave this here to stop others asking the same dumb question?
Solution:
in phpBB config set the cookie domain to the highest common subdomain (or just the domain) mine was: fiestatime.amigadude.com