Rename your .htaccess file and test.

Seems to me
Code:
RewriteEngine On
RewriteCond %{SERVER_PORT} 80
RewriteRule ^(.*)$ https://mysite.com/$1 [R=301,L]
is pushing everything to secure....but you have
Code:
define('HTTP_SERVER', 'http://www.mysite.com');
in the includes/configure.php