[C.Birch]

no in vb3.inc.php

find:

$user = db_query("SELECT userid, username, usergroupid, membergroupids, password, salt, pmunread as unreadpms FROM {prefix}user WHERE userid=" . $_COOKIE["bbuserid"] . " LIMIT 1");

replace with:

$user = db_query("SELECT userid, username, usergroupid, membergroupids, password, salt, pmunread as unreadpms FROM {prefix}user WHERE userid=" . $_COOKIE["vbuserid"] . " LIMIT 1");