Database error in vBulletin 3.6.6:

Invalid SQL:

SELECT COUNT(*) AS users
FROM user
WHERE userid <> 2
AND
(
usergroupid IN(6)
OR FIND_IN_SET('6', membergroupids)
);

MySQL Error : Illegal mix of collations (latin1_swedish_ci,COERCIBLE) and (utf8_general_ci,IMPLICIT) for operation 'find_in_set'
Error Number : 1267
Date : Tuesday, July 3rd 2007 @ 01:39:44 AM
Script : http://www.xxxxx.com/admincp/user.php?do=update
Referrer : http://www.xxxxx.com/admincp/user.php?do=edit&u=2
IP Address : 81.214.150.XXX
Username : Dream
Classname : vb_database