Database error in vBulletin 2.2.8:

Invalid SQL:
SELECT DISTINCT privatemessage.*, user.username AS tousername, user.emailonpm, user.invisible,
user.lastactivity, icon.iconpath, session.userid AS sessionuserid
FROM privatemessage
LEFT JOIN user ON (user.userid = privatemessage.touserid)
LEFT JOIN icon ON (icon.iconid = privatemessage.iconid)
LEFT JOIN session ON (session.userid = user.userid
AND session.userid <> 0 AND user.invisible = 0 AND session.lastactivity>0)
WHERE fromuserid=2
AND folderid <> -1
AND receipt > 0

ORDER BY dateline DESC
mysql error: Lost connection to MySQL server during query

mysql error number: 2013

Database error in vBulletin 2.2.8:

Invalid SQL: UPDATE session SET lastactivity=1043351167,location='/upload/private2.php?s=&daysprune=' WHERE sessionhash='a6964066f1baaa54febeb7b6bc2c2305'
mysql error: MySQL server has gone away

mysql error number: 2006

When a user clicks on PM tracking... it causes mysql to crash and the resulting error is the above.

Can I disable PM tracking and/or does anyone know the fix?