problemas con la la busqueda en mi foro

[saulos]

buenas tengo problemas cuando le hago clic en buscar y el buscar en los foros me sale el error siguiente:

Database error
The Cusco Descargas database has encountered a problem.
Please try the following:

* Load the page again by clicking the Refresh button in your web browser.
* Open the www.************.com home page, then try to open another page.
* Click the Back button to try another link.

The www.************.com forum technical staff have been notified of the error, though you may contact them if the problem persists.

We apologise for any inconvenience.

Database error in vBulletin 3.6.4:

Invalid SQL:

SELECT * FROM search AS search
WHERE searchhash = 'd825e91f3246c9b2fe567033fe1ab243'
AND userid = 1
AND completed = 1;

MySQL Error : Unknown column 'completed' in 'where clause'
Error Number : 1054
Date : Friday, March 16th 2007 @ 09:13:43 AM
Script : http://www.*********.com/forums/search.php?do=process
Referrer : http://www.*********.com/forums/?styleid=25
IP Address : 190.40.252.***
Username : saulosweb
Classname : vb_database

diganme a que se debe este problema y como es que puedo solucionarlo
de antemano gracias la version de mi vbulletin es el 3.6.4