=== modified file 'modules/user/user.module'
--- modules/user/user.module	2008-05-26 17:12:54 +0000
+++ modules/user/user.module	2008-05-30 20:58:37 +0000
@@ -81,6 +81,10 @@ function user_theme() {
     'user_signature' => array(
       'arguments' => array('signature' => NULL),
     ),
+    'user_no_cookie' => array(
+      'file' => 'user.pages.inc',
+      'arguments' => array('domain' => NULL),
+    ),
   );
 }
 
@@ -943,6 +947,13 @@ function user_menu() {
     'access callback' => 'user_is_anonymous',
     'type' => MENU_LOCAL_TASK,
   );
+  $items['user/no-cookie'] = array(
+    'title' => 'Please enable cookies',
+    'page callback' => 'user_no_cookie',
+    'access callback' => TRUE,
+    'type' => MENU_CALLBACK,
+    'file' => 'user.pages.inc',
+  );
   $items['user/reset/%/%/%'] = array(
     'title' => 'Reset password',
     'page callback' => 'drupal_get_form',
@@ -1344,7 +1355,10 @@ function user_login_submit($form, &$form
   global $user;
   if ($user->uid) {
     $form_state['redirect'] = 'user/' . $user->uid;
-    return;
+  }
+  elseif (!$_COOKIE) {
+    unset($_REQUEST['destination']);
+    drupal_goto('user/no-cookie');
   }
 }
 

=== modified file 'modules/user/user.pages.inc'
--- modules/user/user.pages.inc	2008-04-14 17:48:33 +0000
+++ modules/user/user.pages.inc	2008-05-30 20:56:13 +0000
@@ -363,3 +363,11 @@ function user_page() {
     return drupal_get_form('user_login');
   }
 }
+
+function user_no_cookie() {
+  return theme('user_no_cookie', ini_get('session.cookie_domain'));
+}
+
+function theme_user_no_cookie($domain) {
+  return t('It seems that your browser does not accept cookies. To log into this site, you need to accept cookies from the domain @domain.', array('@domain' => $domain));
+}