protected function _notFound($page)
    {
        if ($class = $this->_getPageClass($this->_not_found)) {
            $obj = Solar::factory($class);
            $obj->setFrontController($this);
            $content = $obj->fetch($uri);
        } else {
            $content = "<html><head><title>Not Found</title>"
                     . "<body><h1>404 Not Found</h1><p>"
                     . htmlspecialchars("Page controller for '$page' not found.")
                     . "</p></body></html>";
        }
        
        $response = Solar::factory('Solar_Http_Response');
        $response->setStatusCode(404);
        $response->content = $content;
        
        return $response;
    }