[Database error] مشكلة بعد الترقية من النسخة 3.84 الى 4.0.8 لا استطيع اضافة مواضيع

Database error in vBulletin 4.0.8:

Invalid SQL:

			SELECT prefix.*, prefixpermission.usergroupid AS restriction
			FROM forumprefixset AS forumprefixset
			INNER JOIN prefixset AS prefixset ON (prefixset.prefixsetid = forumprefixset.prefixsetid)
			INNER JOIN prefix AS prefix ON (prefix.prefixsetid = prefixset.prefixsetid)
			LEFT JOIN prefixpermission AS prefixpermission ON (prefix.prefixid = prefixpermission.prefixid)
			WHERE forumprefixset.forumid = 15
			ORDER BY prefixset.displayorder, prefix.displayorder;

MySQL Error   : Illegal mix of collations (latin1_general_cs,IMPLICIT) and (latin1_swedish_ci,IMPLICIT) for operation '='
Error Number  : 1267
Request Date  : Sunday, March 4th 2012 @ 11:28:22 AM
Error Date    : Sunday, March 4th 2012 @ 11:28:22 AM
Script        : http://.com/vb/newthread.php?do=newthread&f=15
Referrer      : http://.com/vb/login.php?do=login
IP Address    : 10
Username      :  
Classname     : vB_Database
MySQL Version : 5.1.56