if the confirm page is not directing to the success page on the order success, it sounds like there is a php error happening that is preventing the redirect.
add the following code at line 1 of the confirm page to turn error reporting on:
<?php
error_reporting(E_ALL);
ini_set('display_errors','on');
?>
can you reproduce the problem?
If a php error is occurring, then is should show at the top of the confirm page.