more than 1000 database errors daily

[elbacha]

Hello all

all members in my forum are suffering and don?t have ( from time to time ) access since the upgrade to the version 3.7.
we are often facing this problem in our vBulletin forum andI am receiving many database errors and here an example on location _http://www.marahibsat.com/forum

Database error in vBulletin 3.7.2:

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 > 1215032688
ORDER BY username ASC, lastactivity DESC;

MySQL Error : Out of memory (Needed 13421600 bytes)
Error Number : 5
Request Date : Wednesday, July 2nd 2008 @ 06:04:48 PM
Error Date : Wednesday, July 2nd 2008 @ 06:05:02 PM
Script : http://www.marahibsat.com/forum/show...=16742&page=25
Referrer : http://www.marahibsat.com/forum/forumdisplay.php?f=186
IP Address : xx.149.93.xxx
Username : saed
Classname : vB_Database
MySQL Version : 5.0.45

please tell me what is wrong ?

Thank you in advance.