Help, Database Error 1052 when I try to send mail to users by usergroupid

[smdani]

Suddenly I noticed that my ?send mail to users? option didn?t work properly, I suppose that a plugin breaks it, but I don?t know which or when could be and how to fix.

The problem:
In the admincp >> user >> send mail to users
I select one or various usergroups to send them a mail, and when I click send, I get this database error:

 Database error in vBulletin 3.5.0:

Invalid SQL:

				SELECT user.userid, user.usergroupid, user.username, user.email, user.joindate,
					useractivation.activationid
				FROM user AS user
				LEFT JOIN userfield AS userfield ON (userfield.userid = user.userid)
				LEFT JOIN usertextfield AS usertextfield ON (usertextfield.userid = user.userid)
				LEFT JOIN useractivation AS useractivation ON (useractivation.userid = user.userid AND useractivation.type = 0)
				WHERE 
		1=1 AND (usergroupid = 3)
		AND user.email <> ''
		
				ORDER BY userid
				LIMIT 0, 500;

MySQL Error  : Column: 'usergroupid' in where clause is ambiguous
Error Number : 1052
Date         : Monday, May 15th 2006 @ 09:41:37 AM
Script       : http://**********/email.php
Referrer     : http:// **********/email.php?do=start

Testing different SQL queries I noticed that if I would remove the part from the ?useractivation.activationid? I mean:

,useractivation.activationid

before the ?from? and

 LEFT JOIN useractivation AS useractivation ON (useractivation.userid = user.userid AND useractivation.type = 0)

The query must be fine, although I looked into the email.php and saw that this line isn?t part of the original code

The questions are ?Am I looking at the right direction? ?Any one knows which hack would did this? Any way ?how can I fix it? I didn?t found where this line was added

Thanks for any help you bring me