Database error in vBulletin 3.6.5:

Invalid SQL:
SELECT userid FROM post where threadid =   AND userid = 1;

MySQL Error  : You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'AND userid = 1' at line 1
Error Number : 1064
Date         : Thursday, April 5th 2007 @ 02:20:47 PM
Script       : http://www.xxxx/vb/admincp/misc.php?do=buildpostcache
Referrer     : http://www.xxxxx./vb/admincp/misc.php?do=chooser
IP Address   : xxxxx
Username     :xxxx
Classname    : xxxxx