Installed this mod in a fresh install of Zen Cart 1.3.8a, and overwrote the files with the modified files. For the first domain, I created a config file and pointed it to the classic template, using a very basic setup:

define('DIR_WS_CATALOG', '/');
define('DIR_WS_HTTPS_CATALOG', '/');
$template_dir = "classic";
define('SITE_NAME','xstore');

I then added this site to all categories using the Admin tool.

The page did not completely display for the site. After troubleshooting, I was able to fix by disabling the whats_new.php and the featured.php sideboxes. Any ideas on what might be the problem?