=== modified file 'includes/form.inc'
--- includes/form.inc	2009-05-24 18:00:08 +0000
+++ includes/form.inc	2009-05-27 13:15:14 +0000
@@ -113,10 +113,6 @@
  *     write data, as this could lead to security issues. It is useful so that
  *     searches do not need to have a form_id in their query arguments to
  *     trigger the search.
- *   - must_validate: Ordinarily, a form is only validated once but there are
- *     times when a form is resubmitted internally and should be validated
- *     again. Setting this to TRUE will force that to happen. This is most
- *     likely to occur during AHAH or AJAX operations.
  * @return
  *   The rendered form or NULL, depending upon the $form_state flags that were set.
  */
@@ -377,6 +373,9 @@
   $form_state['programmed'] = TRUE;
   // Merge in default values.
   $form_state += form_state_defaults();
+  // Reset form validation.
+  // If form validation fails once it fails for all subsequent elements!
+  form_set_error(NULL, '', TRUE);  // reset all form errors
 
   drupal_prepare_form($form_id, $form, $form_state);
   drupal_process_form($form_id, $form, $form_state);
@@ -653,12 +652,6 @@
  *   not be repeated in the submission step.
  */
 function drupal_validate_form($form_id, $form, &$form_state) {
-  static $validated_forms = array();
-
-  if (isset($validated_forms[$form_id]) && empty($form_state['must_validate'])) {
-    return;
-  }
-
   // If the session token was set by drupal_prepare_form(), ensure that it
   // matches the current user's session.
   if (isset($form['#token'])) {
@@ -669,7 +662,6 @@
   }
 
   _form_validate($form, $form_state, $form_id);
-  $validated_forms[$form_id] = TRUE;
 }
 
 /**