Error with private messages
 

I have recently installed vBulletin but at times when you try and send a PM you get the following error:

Quote:
Database error in vBulletin 3.6.8:

Invalid SQL:
INSERT INTO vbull_pm (pmtextid, userid) VALUES (42, );

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 1
Error Number : 1064
Date : Monday, May 11th 2009 @ 11:34:43 PM
Script : http://domain/forum/private.php?do=insertpm&pmid=64
Referrer : http://domain/forum/private.php?do=newpm&pmid=64
IP Address : ip address
Username : username
Classname : vB_Database
It doesn't happen all the time, but is a bit annoying.

Any suggestions on how I can fix this?