Index: submenutree.module
===================================================================
RCS file: /cvs/drupal-contrib/contributions/modules/submenutree/submenutree.module,v
retrieving revision 1.4.2.5
diff -u -r1.4.2.5 submenutree.module
--- submenutree.module	12 Jan 2010 07:28:59 -0000	1.4.2.5
+++ submenutree.module	19 Jan 2010 06:12:04 -0000
@@ -37,7 +37,10 @@
  * Implementation of hook_form_alter().
  */
 function submenutree_form_alter(&$form, $form_state, $form_id) { 
-  if ($form['#id'] == 'node-form') {
+  if (isset($form['#node']) && $form['#node']->type .'_node_form' == $form_id
+        // Check that the menu fieldset still exists.
+        && isset($form['menu'])) {
     $node = $form['#node'];
     // Inject some sane defaults
     if (empty($node->submenutree_enable)) {