MySQL Error

[magicpatch]

Hi,
We have an error which appears for only some users, probably 3 out of the entire forum database, any ideas what is causing it?

Database error in vBulletin 3.0.7:

Invalid SQL: 
 	SELECT user.avatarid, user.avatarrevision, avatarpath, NOT ISNULL(avatardata) AS hascustom, customavatar.dateline
		FROM user AS user
		LEFT JOIN avatar AS avatar ON avatar.avatarid = user.avatarid
		LEFT JOIN customavatar AS customavatar ON customavatar.userid = user.userid
		WHERE user.userid =
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 5

mysql error number: 1064

[Reeve of Shinra]

What version of php and mysql are you running? You can find that out in your admincp -> Maintence -> phpinfo

edit: if its just three users, try uploading a different avatar for them. Maybe the file is corrupt.