Index: privatemsg_filter/privatemsg_filter.module
===================================================================
RCS file: /cvs/drupal-contrib/contributions/modules/privatemsg/privatemsg_filter/privatemsg_filter.module,v
retrieving revision 1.1.2.17.2.27
diff -u -p -r1.1.2.17.2.27 privatemsg_filter.module
--- privatemsg_filter/privatemsg_filter.module	15 Aug 2010 23:45:49 -0000	1.1.2.17.2.27
+++ privatemsg_filter/privatemsg_filter.module	5 Sep 2010 07:26:37 -0000
@@ -702,7 +702,7 @@ function privatemsg_filter_query_private
  * Hook into the view messages page to add a form for tagging purposes.
  */
 function privatemsg_filter_page_alter(&$page) {
-  if (isset($page['content']['system_main']['messages']) && count($page['content']['system_main']['messages']) && privatemsg_user_access('tag private messages')) {
+  if (isset($page['content']['system_main']['messages']) && count($page['content']['system_main']['messages']) && isset($page['content']['system_main']['participants']) && privatemsg_user_access('tag private messages')) {
     $page['content']['system_main']['tags'] = drupal_get_form('privatemsg_filter_form');
     $page['content']['system_main']['tags']['#weight'] = variable_get('privatemsg_filter_tagfield_weight', 10);
   }