Index: includes/form.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/form.inc,v
retrieving revision 1.265.2.34
diff -u -p -r1.265.2.34 form.inc
--- includes/form.inc	6 Aug 2010 11:02:49 -0000	1.265.2.34
+++ includes/form.inc	29 Oct 2010 02:24:37 -0000
@@ -2277,6 +2277,7 @@ function form_clean_id($id = NULL, $flus
     $seen_ids = array();
     return;
   }
+  $id = preg_replace('/[^\x{002D}\x{0030}-\x{0039}\x{0041}-\x{005A}\x{005F}\x{0061}-\x{007A}\x{00A1}-\x{FFFF}]/u', '', $id);
   $id = str_replace(array('][', '_', ' '), '-', $id);
 
   // Ensure IDs are unique. The first occurrence is held but left alone.