[Lynne]

It almost looks like you have it disabled. Check the permissions in the usergroup manager > usergroups > sig permissions and also in vboptions > bb code settings (I think you said you already checked that).

Try disabling your 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);