I assume you have checked the permissions for the forum in the Forum Permissions page?
Try disabling your modifications/plugins and see if you still have this problem.
Note: To temporarily disable the plugin system, edit config.php and add this line right under <?php
PHP Code:
define('DISABLE_HOOKS', true);
the permissions are in order. i tried to uninstall the hasann subforum manager and disable it but it doesnt go away