[JamesAB]

You can use the global_start hook and tell it to bypass this on certain pages.

Here's a snippet I used.

PHP Code:

if (in_array(THIS_SCRIPT, array('400_forum', '401_forum', '403_forum',
    '404_forum', '500_forum')))
{
    $vbulletin->options['bbactive'] = true;
    $servertoobusy = 0;
    $vbulletin->userinfo['permissions']['forumpermissions'] |= $vbulletin->
        bf_ugp_forumpermissions['canview'];
} 


Just change the THIS_SCRIPT array to contain your external pages.