Index: modules/system/system.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.module,v
retrieving revision 1.842
diff -u -9 -p -r1.842 system.module
--- modules/system/system.module	16 Nov 2009 05:11:01 -0000	1.842
+++ modules/system/system.module	18 Nov 2009 22:10:32 -0000
@@ -1789,19 +1789,19 @@ function system_user_timezone(&$form, &$
     '#collapsible' => TRUE,
   );
   $form['timezone']['timezone'] = array(
     '#type' => 'select',
     '#title' => t('Time zone'),
     '#default_value' => isset($account->timezone) ? $account->timezone : ($account->uid == $user->uid ? variable_get('date_default_timezone', '') : ''),
     '#options' => system_time_zones($account->uid != $user->uid),
     '#description' => t('Select the desired local time and time zone. Dates and times throughout this site will be displayed using this time zone.'),
   );
-  if (!isset($account->timezone) && $account->uid == $user->uid) {
+  if (!isset($account->timezone) && $account->uid == $user->uid && empty($form_state['input']['timezone'])) {
     $form['timezone']['#description'] = t('Your time zone setting will be automatically detected if possible. Please confirm the selection and click save.');
     $form['timezone']['timezone']['#attributes'] = array('class' => array('timezone-detect'));
     drupal_add_js('misc/timezone.js');
   }
 }
 
 /**
  * Implement hook_block_info().
  */