Index: includes/locale.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/locale.inc,v
retrieving revision 1.258
diff -u -p -r1.258 locale.inc
--- includes/locale.inc	30 Jul 2010 02:47:27 -0000	1.258
+++ includes/locale.inc	29 Sep 2010 11:06:21 -0000
@@ -238,11 +238,27 @@ function locale_language_switcher_sessio
  * Rewrite URLs for the URL language provider.
  */
 function locale_language_url_rewrite_url(&$path, &$options) {
+  static $drupal_static_fast;
+  if (!isset($drupal_static_fast)) {
+    $drupal_static_fast['languages'] = &drupal_static(__FUNCTION__);
+  }
+  $languages = &$drupal_static_fast['languages'];
+
+  if (!isset($languages)) {
+    $languages = language_list('enabled');
+    $languages = array_flip(array_keys($languages[1]));
+  }
+
   // Language can be passed as an option, or we go for current URL language.
   if (!isset($options['language'])) {
     global $language_url;
     $options['language'] = $language_url;
   }
+  // We allow only enabled languages here.
+  elseif (!isset($languages[$options['language']->language])) {
+    unset($options['language']);
+    return;
+  }
 
   if (isset($options['language'])) {
     switch (variable_get('locale_language_negotiation_url_part', LOCALE_LANGUAGE_NEGOTIATION_URL_PREFIX)) {