Index: modules/system/system.admin.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.admin.inc,v
retrieving revision 1.262
diff -u -p -r1.262 system.admin.inc
--- modules/system/system.admin.inc	7 Mar 2010 07:36:27 -0000	1.262
+++ modules/system/system.admin.inc	9 Mar 2010 19:45:01 -0000
@@ -425,10 +425,12 @@ function system_theme_default() {
     if (!empty($themes[$theme])) {
       // Enable the theme if it is currently disabled.
       if (empty($themes[$theme]->status)) {
-       theme_enable(array($theme));
+        theme_enable(array($theme));
       }
       // Set the default theme.
       variable_set('theme_default', $theme);
+      // Rebuild menu items that take the default theme into account.
+      menu_rebuild();
       // The status message depends on whether an admin theme is currently in use:
       // a value of 0 means the admin theme is set to be the default theme.
       $admin_theme = variable_get('admin_theme', 0);