Database error in vBulletin 3.7.0:

Invalid SQL:
SELECT DISTINCT userid FROM session WHERE userid <> 0 AND lastactivity > 1217583602;

MySQL Error   : Out of memory (Needed 838856 bytes)
Error Number  : 5
Request Date  : Friday, August 1st 2008 @ 02:55:02 AM
Error Date    : Friday, August 1st 2008 @ 02:55:03 AM
Script        : http://www.hayatimizfutbol.com/admincp/index.php?do=home
Referrer      : http://www.hayatimizfutbol.com/admincp/
IP Address    : 85.106.250.143
Username      : kurac
Classname     : vB_Database
MySQL Version : 5.0.45-log