3.6.4 e geçiş yaptıktan sonra sürekli db hatası vermeye başladı site normal halinde dururken de hata veriyor e-mail gönderirken de

Database error in vBulletin 3.6.4:

Invalid SQL:

		SELECT user.username, user.usergroupid, user.membergroupids,
			session.userid, session.inthread, session.lastactivity,
			IF(user.displaygroupid = 0, user.usergroupid, user.displaygroupid) AS displaygroupid, infractiongroupid,
			IF(user.options & 512, 1, 0) AS invisible
		FROM session AS session
		LEFT JOIN user AS user ON(user.userid = session.userid)
		WHERE session.lastactivity > 1166259428
		ORDER BY  username ASC, lastactivity DESC;

MySQL Error  : Lost connection to MySQL server during query
Error Number : 2013
Date         : Saturday, December 16th 2006 @ 05:17:09 PM
Script       : http://www.xxxxxxxxxx/index.html
Referrer     : http://www.xxxxxxxx
IP Address   : xxxxx
Username     : xxxx
Classname    : xxx_xxx