--- drupal7-7.14.orig/modules/user/user.module
+++ drupal7-7.14/modules/user/user.module
@@ -1122,7 +1122,7 @@ function user_account_form(&$form, &$for
   $form['account']['roles'] = array(
     '#type' => 'checkboxes',
     '#title' => t('Roles'),
-    '#default_value' => (!$register && isset($account->roles) ? array_keys($account->roles) : array()),
+    '#default_value' => (!$register && !empty($account->roles) ? array_keys(array_filter($account->roles)) : array()),
     '#options' => $roles,
     '#access' => $roles && user_access('administer permissions'),
     DRUPAL_AUTHENTICATED_RID => $checkbox_authenticated,
