Define page editor not working once site moved

[dsided]

I've just moved my site from the staging server to the live server, however the Define Page Editor doesn't work.

When I choose a file from the admin it doesn't load.

My error_log contains the following:

[Thu Dec 11 17:11:55 2008] [error] [client 8.10.2.8] PHP Fatal error:  messageStack::require() [<a href='function.require'>function.require</a>]: Failed opening required 'DIR_WS_TEMPLATEStemplate_default/templates/tpl_message_stack_default.php' (include_path='.:/usr/local/psa/apache/lib/php:/usr/local/share/pear') in /usr/local/psa/home/vhosts/website.com/httpdocs/admin/includes/classes/message_stack.php on line 86, referer: http://www.website.com/zenadmin/define_pages_editor.php?define_it=12&action=new_page

I thought my includes/configure.php was missing the trailing slash, however it says:

  define('HTTP_SERVER', 'http://www.website.com');
  define('HTTPS_SERVER', 'https://www.website.com');  
  define('DIR_WS_CATALOG', '/');
  define('DIR_WS_HTTPS_CATALOG', '/');
define('DIR_WS_TEMPLATES', DIR_WS_INCLUDES . 'templates/');

Any ideas?