Index: plugins/archive/archive.php
===================================================================
--- plugins/archive/archive.php	(revision 3250)
+++ plugins/archive/archive.php	(working copy)
@@ -22,7 +22,8 @@
     
     $rcmail = rcmail::get_instance();
     if ($rcmail->task == 'mail' && ($rcmail->action == '' || $rcmail->action == 'show')
-      && ($archive_folder = $rcmail->config->get('archive_mbox'))) {
+      && ($archive_folder = $rcmail->config->get('archive_mbox'))
+      && !empty($rcmail->user->ID)) {
 
       $skin_path = $this->local_skin_path();