Index: includes/common.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/common.inc,v
retrieving revision 1.674
diff -u -p -r1.674 common.inc
--- includes/common.inc	13 Jul 2007 20:07:14 -0000	1.674
+++ includes/common.inc	15 Jul 2007 18:07:06 -0000
@@ -340,8 +340,13 @@ function drupal_not_found() {
 
   $path = drupal_get_normal_path(variable_get('site_404', ''));
   if ($path && $path != $_GET['q']) {
+    menu_set_active_item($path);
     $return = menu_execute_active_handler($path);
   }
+  else {
+    // Clear out the invalid path.
+    menu_set_active_item('');
+  }
 
   if (empty($return)) {
     drupal_set_title(t('Page not found'));
@@ -365,8 +370,13 @@ function drupal_access_denied() {
 
   $path = drupal_get_normal_path(variable_get('site_403', ''));
   if ($path && $path != $_GET['q']) {
+    menu_set_active_item($path);
     $return = menu_execute_active_handler($path);
   }
+  else {
+    // Clear out the invalid path.
+    menu_set_active_item('');
+  }
 
   if (empty($return)) {
     drupal_set_title(t('Access denied'));
Index: includes/menu.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/menu.inc,v
retrieving revision 1.186
diff -u -p -r1.186 menu.inc
--- includes/menu.inc	9 Jul 2007 18:08:15 -0000	1.186
+++ includes/menu.inc	15 Jul 2007 18:07:07 -0000
@@ -1155,7 +1155,11 @@ function menu_get_active_menu_name() {
   return menu_set_active_menu_name();
 }
 
-function menu_set_active_item() {
+/**
+ * Set the active path.
+ */
+function menu_set_active_item($path) {
+  $_GET['q'] = $path;
 }
 
 /**