diff -ruN drupal-2005-12-31/modules/user.module drupal-2005-12-31a/modules/user.module
--- drupal-2005-12-31/modules/user.module	2005-12-31 14:00:04.000000000 +0100
+++ drupal-2005-12-31a/modules/user.module	2005-12-31 20:22:20.000000000 +0100
@@ -1304,6 +1304,12 @@
 
 function user_edit_submit($form_id, $form_values) {
   $account = $form_values['_account'];
+  // clean out stuff that isn't to be saved
+  $form_values['_account'] = NULL;
+  $form_values['_category'] = NULL;
+  $form_values['submit'] = NULL;
+  $form_values['delete'] = NULL;
+  $form_values['form_id'] = NULL;
   user_save($account, $form_values, $form_values['_category']);
   // Delete that user's menu cache.
   cache_clear_all('menu:'. $account->uid, TRUE);