Never head or if logging the user off of Joomla before... send more information about that...
On your phpBB login... send more information..
Have you imported or exported users from the control panel?
Have you manually setup the phpbb ID for any users?
Have you created new users since installing the connector?
Are those users having problems?
Have not tested it yet with phpbb 2.0.20 so I don't know if the session file has changed or not... (I think it did so the line numbers may not match)
Once we get more info lets see where we are at...
Greg
CB3PD Developer - CB Connector (formerly phpBB Connector) plugin