I am having this same problem. I am running a phpbb3 forum that I currently have synchronized through Rokbridge. Whenever a user logs into either the Joomla system or phpbb3, the bridge copies the username, status and password over to the Joomla database from phpbb3.
Well, some of those usernames that have made their way over (mine included) have a space in them. As a result, the users can now log into Joomla but they can't modify their profiles in CB because the modification screen demands that they change their usernames (which they aren't allowed to do.) So, I end up with users who can't access their accounts and are forced (for no valid reason I can tell) to change their usernames when it is impossible to do so.
Is it possible to change the username policy so that they can include spaces and if so, does anyone have any clue how to do it?
Thanks for all your help everyone. I am hoping that this works out to be a great application.