Paste this code into a file in your admin directory, then run it, it should clear the extra fields for you. Then run step 1 of the install_stealth.php file to re-add the extra fields.
PHP Code:
<?php
require("./global.php");
cpheader();
$DB_site->query("DELETE FROM setting WHERE varname='WOLsadmin'");
$DB_site->query("DELETE FROM setting WHERE varname='WOLadstr'");
$DB_site->query("DELETE FROM setting WHERE varname='WOLsmods'");
$DB_site->query("DELETE FROM setting WHERE varname='WOLsmodstr'");
$DB_site->query("DELETE FROM setting WHERE varname='WOLsmod'");
$DB_site->query("DELETE FROM setting WHERE varname='WOLmodstr'");
echo "Records erased!";
cpfooter();
?>
As for guests being stealthed, I'm not sure. Guests don't have usergroupid's, so they shouldn't get stealthed. Are your guests getting usergroupid 5, 6, or 7? Go to Admin Control Panel -> User Groups -> Modify, put your mouse over the "edit" link of your admins, super mods, and mods groups, and look at the URL that link goes to, the last part of the URL should contain the usergroupid.
Kathi