error con el mgc chatbox

Database error in vBulletin 3.6.8:

Invalid SQL:

SELECT id,u.username,u.usergroupid,date,chat,u.userid AS userid

FROM mgc_chatbox AS mgc_cb
LEFT JOIN user AS u ON(mgc_cb.userid = u.userid)

WHERE chat NOT REGEXP '^(/[tT][eE][aA][mM])' AND touserid='0'
ORDER BY date DESC
LIMIT 15;

MySQL Error : MySQL server has gone away
Error Number : 2006
Date : Monday, June 2nd 2008 @ 04:15:18 PM
Script : mipagina/foro/mgc_chatbox.php
Referrer : mipagina/foro.php?
IP Address : 190.48.254.121
Username : Golem
Classname : vB_Database