msql error

[mystic10]

i went to my usercp and under moderation deleted thread...everything else is working fine..except this...whenever i press on the deleted thread this is the error i get:

Database error in vBulletin 3.6.8:

Invalid SQL:

SELECT * FROM user as u
LEFT JOIN usergroup as ug ON (u.usergroupid = ug.usergroupid)
LEFT JOIN post as p ON (u.userid = p.userid)
WHERE postid=;

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 '' at line 4
Error Number : 1064
Date : Wednesday, February 13th 2008 @ 04:01:39 PM
Script : http://www.yah00-city.com/moderation...s&type=deleted
Referrer : http://www.yah00-city.com/usercp.php
IP Address :
Username :
Classname : vB_Database

please help