[nhawk]

$user can't be used twice the way you're using it. The while loop will never end.

while ($user = $vbulletin->db->fetch_array($result))
{
     // set last user processed
     $lastuser = $user['userid'];

     // copy the ban liftdate before it is removed by fetch_userinfo
     $liftdate = $user['liftdate'];

     // fetch their info
     $user = fetch_userinfo($user['userid']);