Hi Greg and thanx for your help. Unfortunately i tried the way u suggested but nothing happens. The new login window pops up, i re-login with my admin credentials and this is what happens:
while i log in into the new window, the other window where i clicked on plugin control panel goes automatically back to the main CB plugin window. I do the login in the new pop up window, close it and when i try again to access the phpbb connector it reload in the main window the login panel of joomla...
instead if i try to access the plugin from the popup window it only gives me a 'phpbb connector plugin succesfully installed' message appearing on the general cb plugin page...but nothing happens with the users, no synchro i mean..i'm just stuck :/ (i'm sorry about my english..italy here )