[kh99]

OK, try these two plugins:

hook location forumhome_whovisited:

$newarray = array();
$count = 0;
foreach ($wgo_members_list AS &$member)
{
   if (!is_member_of($member, 3, 4))
   {
       $count++;
       $newarray[$count] = &$member;
       $newarray[$count]['comma'] = $vbphrase['comma_space'];
   }
}
if ($count)
{
    $newarray[$count]['comma'] = '';
}
$wgo_members_list = &$newarray;

hook location forumhome_loggedinuser:

if (is_member_of($loggedin, 3, 4))
{
   $loggedin['lastactivity'] = 0;
}