Index: wp-admin/includes/post.php
===================================================================
--- wp-admin/includes/post.php	(revision 19641)
+++ wp-admin/includes/post.php	(working copy)
@@ -973,7 +973,8 @@
 }
 
 function _edit_attachments_query_helper($where) {
-	return $where .= ' AND post_parent < 1';
+	global $wpdb;
+	return $where .= ' AND ' . $wpdb->posts . '.post_parent < 1';
 }
 
 /**