Well, when I looked at the site just a few minutes ago, there was no "500 Internal Server" error, just no stylesheets and missing images/buttons.

As this is Fasthosts we're talking about there's one thing he can try, and that's to remove the .htaccess file from the includes folder, or edit it to read:

Code:
<Files "*.php">
Order Deny,Allow
Deny from all
</Files>
Vger