To elaborate, does Coppermine create and maintain its own separate user database or does it integrate with and use only the forum database for user validation and storage of its data?
I use the same forum software that you are using here and am switching my front end portal from one CMS to MKPortal because I find the integration of MKPortal with Simple Machines Forum to be a much better affair than the glitchy mod that is available for my old CMS. My old CMS maintained its own separate user DB and only used the forum DB as for simple validation of users. If a user logged into the CMS and then went to the forum index page they almost always ended up having to log-in the forums again.
What I want is a reasonably stable unified log-in procedure that will only require one log-in to access the restricted content on my sites.