Go to your forum's root directory, and look for the directory "includes" and in that directory you should find the file "config.php". Download that file to your hard drive, and use an editor such as Notepad++ to add the line of code I posted to the top of the file, just below the opening PHP tag, so that the beginning to the file looks like:
PHP Code:
<?php
define('DISABLE_HOOKS', true);
Once you are finished making the edit, then rename the existing file "config.php" on your server to "config_original.php" so in case you messed up editing the file, you rename this back to "config.php" to restore things back to the starting point.
Next, upload the edited file to your server (in the "includes" folder), and you should then be able to get into your AdminCP to fix whatever issue there is. Once done, comment out the line you added to "config.php" and upload the file again to your server.