Database error on last posts

[kryssluck]

When i click the last message on the category, I am receiving this error.

This will occur only when login is made. I tried to turn off all extensions. I tried to repair the post table.

What should I do ?

Database error in vBulletin 3.8.9:

Invalid SQL:

			SELECT MIN(postid) AS postid
			FROM post
			WHERE threadid = 20
				AND visible = 1
				AND dateline > 1441226037
				AND userid NOT IN (//)
			LIMIT 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 '//)
			LIMIT 1' at line 6
Error Number  : 1064
Request Date  : Wednesday, September 2nd 2015 @ 09:58:36 PM
Error Date    : Wednesday, September 2nd 2015 @ 09:58:36 PM
Script        : http://******.com/showthread.php?t=20&goto=newpost
Referrer      : http://*****.com/
IP Address    : 78.177.*****
Username      : K******
Classname     : vB_Database
MySQL Version : 5.5.45

PHP Version 5.4.44

Edit: This error message came up again message editing

Database error in vBulletin 3.8.9:

Invalid SQL:

			SELECT thread.postuserid, COUNT(*) AS threadcount
			FROM thread AS thread
			WHERE thread.postuserid IN (//)
				AND thread.visible = 1
				AND thread.open <> 10
				AND thread.forumid = 52
			GROUP BY thread.postuserid;

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 thread.visible = 1
				AND thread.open <> 10
				AND thread.forumid ' at line 3
Error Number  : 1064
Request Date  : Wednesday, September 2nd 2015 @ 10:14:41 PM
Error Date    : Wednesday, September 2nd 2015 @ 10:14:41 PM
Script        : http://********.com/editpost.php?do=updatepost&postid=28
Referrer      : http://*******.com/guncel-yarismalar/22-asdfasdf.html
IP Address    : 78.177.*****
Username      : K******
Classname     : vB_Database
MySQL Version : 5.5.45