Yes you can use dreamweaver to check it the file should look like this.
PHP Code:
<?php
// phpBB 3.0.x auto-generated configuration file
// Do not change anything in this file!
$dbms = 'mysqli';
$dbhost = 'localhost';
$dbport = '';
$dbname = 'username_databasename';
$dbuser = 'username_databaseusername';
$dbpasswd = 'password for database username';
$table_prefix = 'phpbb_';
$acm_type = 'file';
$load_extensions = '';
@define('PHPBB_INSTALLED', true);
// @define('DEBUG', true);
// @define('DEBUG_EXTRA', true);
?>
this file is written when you first install the forum. now if you change anything in these lines or within mysql database and the two don't match then you get an error.
One of the main reasons is ether deleting a username from MySql or changing the permissions for that user or password.
$dbhost = 'localhost';
$dbport = '';
$dbname = 'username_databasename';
$dbuser = 'username_databaseusername';
$dbpasswd = 'password for database username';
$table_prefix = 'phpbb_';
the lines above should be checked that they match what is in MySql Database in c-panel.
one way to check is to download a config.php file from one of your other forums and upload it to the forum with the problem. ( make sure you have a copy of the originals saved ) if it connects to the second database and shows ok then the problem is in the lines above not matching.
warning though this only works if neither forums have been modified or have but with the same modification.