Back button doesn't refresh page if URL contains GET parameters or trailing slash?
Try setting these headers and see if that makes the behavior consistent in both scenarios:
$this->output->set_header("Cache-Control: no-store, no-cache, must-revalidate");$this->output->set_header("Cache-Control: post-check=0, pre-check=0");$this->output->set_header("Pragma: no-cache");$this->output->set_header("Expires: Sat, 26 Jul 1997 05:00:00 GMT");More info: http://ellislab.com/codeigniter/user-guide/libraries/output.html