Index: privatemsg.module
===================================================================
RCS file: /cvs/drupal/contributions/modules/privatemsg/privatemsg.module,v
retrieving revision 1.120
diff -u -p -r1.120 privatemsg.module
--- privatemsg.module	25 Feb 2010 18:33:50 -0000	1.120
+++ privatemsg.module	3 Mar 2010 17:47:42 -0000
@@ -792,6 +792,7 @@ function privatemsg_sql_load(&$fragments
     $fragments['query_args']['where'][]  = $account->uid;
   }
   $fragments['order_by'][] = 'pm.timestamp ASC';
+  $fragments['order_by'][] = 'pm.mid ASC';
 }
 
 /**
@@ -853,6 +854,8 @@ function privatemsg_sql_participants(&$f
   $fragments['inner_join'][]  = 'INNER JOIN {users} u ON (u.uid = pmi.uid)';
   $fragments['where'][]       = 'pmi.thread_id = %d';
   $fragments['query_args']['where'][]  = $thread_id;
+
+  $fragments['order_by'][]    = 'pmi.uid ASC';
 }
 
 /**
Index: privatemsg.test
===================================================================
RCS file: /cvs/drupal/contributions/modules/privatemsg/privatemsg.test,v
retrieving revision 1.7
diff -u -p -r1.7 privatemsg.test
--- privatemsg.test	17 Feb 2010 10:05:45 -0000	1.7
+++ privatemsg.test	3 Mar 2010 17:47:42 -0000
@@ -315,7 +315,7 @@ class PrivatemsgTestCase extends DrupalW
     );
 
     $this->drupalPost(NULL, $reply, t('Send message'));
-    $this->assertText(t('A message has been sent to @recipient, @author.', array('@recipient' => $recipient->name, '@author' => $author->name)), 'Reply has been sent.');
+    $this->assertText(t('A message has been sent to @author, @recipient.', array('@recipient' => $recipient->name, '@author' => $author->name)), 'Reply has been sent.');
     $this->assertText($reply['body'], 'New message body displayed.');
 
     $this->drupalPost(NULL, $replyempty, t('Send message'));