Index: includes/common.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/common.inc,v
retrieving revision 1.788
diff -u -p -r1.788 common.inc
--- includes/common.inc	21 Aug 2008 19:36:36 -0000	1.788
+++ includes/common.inc	1 Sep 2008 00:20:03 -0000
@@ -336,16 +336,27 @@ function drupal_site_offline() {
  */
 function drupal_not_found() {
   drupal_set_header('HTTP/1.1 404 Not Found');
-
   watchdog('page not found', check_plain($_GET['q']), NULL, WATCHDOG_WARNING);
 
+  $return = '';
+
+  if (variable_get('site_404_message_display', TRUE)) {
+    $message = variable_get('site_404_message', t('<p>The requested content was not found on this site. The content might have been removed or had its location changed.</p>
+<ul>
+<li> If you typed the URL manually, please check the spelling.</li>
+<li> Visit the front page of <sitename> and browse for the information you want.</li>
+<li> Click the "Back" button of your browser to try another link.</li>
+</ul>'));
+    drupal_set_message(filter_xss_admin($message));
+  }
+
   // Keep old path for reference.
   if (!isset($_REQUEST['destination'])) {
     $_REQUEST['destination'] = $_GET['q'];
   }
 
   $path = drupal_get_normal_path(variable_get('site_404', ''));
-  if ($path && $path != $_GET['q']) {
+  if (!empty($path) && $path != $_GET['q']) {
     // Set the active item in case there are tabs to display, or other
     // dependencies on the path.
     menu_set_active_item($path);
@@ -368,13 +379,25 @@ function drupal_access_denied() {
   drupal_set_header('HTTP/1.1 403 Forbidden');
   watchdog('access denied', check_plain($_GET['q']), NULL, WATCHDOG_WARNING);
 
-  // Keep old path for reference.
+  $return = '';
+
+  if (variable_get('site_403_message_display', TRUE)) {
+    $message = variable_get('site_403_message', t('<p>You do not have permission to view this content.</p>
+<ul>
+<li> You may need to log in.</li>
+<li> Visit the front page of <sitename> and browse for the information you want.</li>
+<li> Click the "Back" button of your browser to try another link.</li>
+</ul>'));
+    drupal_set_message(filter_xss_admin($message));
+  }
+
+  // Keep old path for reference
   if (!isset($_REQUEST['destination'])) {
     $_REQUEST['destination'] = $_GET['q'];
   }
 
   $path = drupal_get_normal_path(variable_get('site_403', ''));
-  if ($path && $path != $_GET['q']) {
+  if (!empty($path) && $path != $_GET['q']) {
     // Set the active item in case there are tabs to display or other
     // dependencies on the path.
     menu_set_active_item($path);
Index: modules/system/system.admin.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.admin.inc,v
retrieving revision 1.86
diff -u -p -r1.86 system.admin.inc
--- modules/system/system.admin.inc	30 Aug 2008 09:49:43 -0000	1.86
+++ modules/system/system.admin.inc	1 Sep 2008 00:20:04 -0000
@@ -1284,23 +1284,66 @@ function system_site_information_setting
  */
 function system_error_reporting_settings() {
 
-  $form['site_403'] = array(
+  $form['403'] = array(
+    '#type' => 'fieldset',
+    '#title' => t('Access denied page'),
+    '#description' => t('These settings apply when the requested document is denied to the current user, i.e. a <em>403 error</em>.'),
+  );
+  $form['403']['site_403'] = array(
     '#type' => 'textfield',
-    '#title' => t('Default 403 (access denied) page'),
+    '#title' => t('Page to display'),
     '#default_value' => variable_get('site_403', ''),
     '#size' => 40,
     '#description' => t('This page is displayed when the requested document is denied to the current user. If unsure, specify nothing.'),
     '#field_prefix' => url(NULL, array('absolute' => TRUE)) . (variable_get('clean_url', 0) ? '' : '?q=')
   );
+  $form['403']['site_403_message_display'] = array(
+    '#type' => 'checkbox',
+    '#title' => t('Display error message'),
+    '#description' => t('Enabling this feature will display the message below when the requested document is denied to the current user, even if <em>"Page to display"</em> is set.'),
+    '#default_value' => variable_get('site_403_message_display', TRUE),
+  );
+  $form['403']['site_403_message'] = array(
+    '#type' => 'textarea',
+    '#title' => t('Message'),
+    '#default_value' => variable_get('site_403_message', t('<p>You do not have permission to view this content.</p>
+<ul>
+<li> You may need to log in.</li>
+<li> Visit the front page of <sitename> and browse for the information you want.</li>
+<li> Click the "Back" button of your browser to try another link.</li>
+</ul>')),
+  );
 
-  $form['site_404'] = array(
+  $form['404'] = array(
+    '#type' => 'fieldset',
+    '#title' => t('File not found page'),
+    '#description' => t('These settings apply when the requested document could not be found, i.e. a <em>404 error</em>.'),
+  );
+  $form['404']['site_404'] = array(
     '#type' => 'textfield',
-    '#title' => t('Default 404 (not found) page'),
+    '#title' => t('Ppage to display'),
     '#default_value' => variable_get('site_404', ''),
     '#size' => 40,
     '#description' => t('This page is displayed when no other content matches the requested document. If unsure, specify nothing.'),
     '#field_prefix' => url(NULL, array('absolute' => TRUE)) . (variable_get('clean_url', 0) ? '' : '?q=')
   );
+  $form['404']['site_404_message_display'] = array(
+    '#type' => 'checkbox',
+    '#title' => t('Display error message'),
+    '#description' => t('Enabling this feature will display the message below when the requested document could not be found, even if <em>"Page to display"</em> is set.'),
+    '#default_value' => variable_get('site_404_message_display', TRUE),
+  );
+  $form['404']['site_404_message'] = array(
+    '#type' => 'textarea',
+    '#title' => t('Message'),
+    '#default_value' => variable_get('site_404_message', t('<p>The requested content was not found on this site. The content might have been removed or had its location changed.</p>
+<ul>
+<li> If you typed the URL manually, please check the spelling.</li>
+<li> Visit the front page of <sitename> and browse for the information 
+ou want.</li>
+<li> Click the "Back" button of your browser to try another link.</li>
+</ul>')),
+   );
 
   $form['error_level'] = array(
     '#type' => 'select', '#title' => t('Error reporting'), '#default_value' => variable_get('error_level', 1),