don't know if this is totally kosher, but so far seems to solve the problem with no side effects (no more PM's to mods and admins after every ticket update)
removed the following:
PHP Code:
// send a PM to all those users
while ($userinfo = $DB_site->fetch_array($updatequery))
{
sendprivatemessage ($userinfo, 'The following ticket has been updated:
[URL]'.$vboptions[bburl].'/helpdesk.php?do=ticket&tid='.$_REQUEST['tid'] . '[/URL]', 'HelpDesk Ticket Update');
}