all the links I see on this page are site relative:
<link href="/styles/starfire_style.css" rel="stylesheet" type="text/css" />
using the site relative links setting in the Site definition is the only way I have ever seen DW force the virtual function to be used.
you can manually edit the code to the require_once function:
<?php
//WA eCart Include
require_once("WA_eCart/starfire2_PHP.php");
?>