Weird problem with SSL

Hi all I have installed an SSL certificate onto my clients site, but I'm getting an error when trying to use a PHP file. The reason I ask is that if I go to: https://directmail.co.uk I get an error of: Forbidden You don't have permission to access / on this server. If I go to: https://directmail.co.uk/index.php3 Then I get a bit of PHP code displayed: <?php $HTTP_GET_VARS[id]=1; include "_inc/_func.php"; include "_inc/_glob.php"; // Send a message to directmail.co.uk telling them that someone has filled in the form if(count($HTTP_POST_VARS)>1) include '_inc/mailing_handler.php'; $PARAMS[local_menu]=''; $PARAMS[page_file]="_inc/_main_content.htm"; include "_inc/_view.htm"; ?> and if I go to: https://directmail.co.uk/information.html which is a 'normal' html file it works fine Any ideas? Thanks Ade