Index: modules/node/content_types.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/node/content_types.inc,v
retrieving revision 1.119
diff -u -p -r1.119 content_types.inc
--- modules/node/content_types.inc	13 Oct 2010 13:43:21 -0000	1.119
+++ modules/node/content_types.inc	20 Nov 2010 14:57:39 -0000
@@ -100,7 +100,7 @@ function node_type_form($form, &$form_st
     '#type' => 'machine_name',
     '#default_value' => $type->type,
     '#maxlength' => 32,
-    '#disabled' => $type->locked,
+    '#disabled' => $type->locked || $type->type !== '',
     '#machine_name' => array(
       'exists' => 'node_type_load',
     ),
Index: modules/taxonomy/taxonomy.admin.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/taxonomy/taxonomy.admin.inc,v
retrieving revision 1.116
diff -u -p -r1.116 taxonomy.admin.inc
--- modules/taxonomy/taxonomy.admin.inc	20 Nov 2010 06:49:47 -0000	1.116
+++ modules/taxonomy/taxonomy.admin.inc	20 Nov 2010 14:58:49 -0000
@@ -151,6 +151,7 @@ function taxonomy_form_vocabulary($form,
     '#machine_name' => array(
       'exists' => 'taxonomy_vocabulary_machine_name_load',
     ),
+    '#disabled' => $vocabulary->machine_name !== '',
   );
   $form['old_machine_name'] = array(
     '#type' => 'value',