Forum Help with understanding database error.
 

I just received an error email from my vB server:

Code:
Database error in vBulletin 4.0.1:

Invalid SQL:

SELECT a.attachmentid
FROM attachment AS a
WHERE
(filedataid = AND userid = 3);

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 = 3)' at line 4
Error Number : 1064
Request Date : Thursday, January 21st 2010 @ 10:56:36 AM
Error Date : Thursday, January 21st 2010 @ 10:56:36 AM
Script : http://xxx.xxx.com/QMS/cron.php?rand=1264067795 / edited for privacy
Referrer : http://xxx.xxx.com/QMS/forumdisplay.php?5-clients / edited for privacy
IP Address : 90.6.99.99 / edited for privacy
Username : Unregistered
Classname : vB_Database
MySQL Version :
Does anyone know what has caused this error and what I should do to fix it? Is it a script error in vB or a setup error in mySQL. Sorry if this is a very basic question, I have zero mySQL knowledge and only use it for vB.