In the configure.php files there's a section:

PHP Code:
// * DIR_WS_* = Webserver directories (virtual/URL)
// these paths are relative to top of your webspace ... (ie: under the public_html or httpdocs folder)
define('DIR_WS_CATALOG''/');
define('DIR_WS_HTTPS_CATALOG''/');

define('DIR_WS_IMAGES''images/');
define('DIR_WS_INCLUDES''includes/');
define('DIR_WS_FUNCTIONS'DIR_WS_INCLUDES 'functions/');
define('DIR_WS_CLASSES'DIR_WS_INCLUDES 'classes/');
define('DIR_WS_MODULES'DIR_WS_INCLUDES 'modules/');
define('DIR_WS_LANGUAGES'DIR_WS_INCLUDES 'languages/');
define('DIR_WS_DOWNLOAD_PUBLIC'DIR_WS_CATALOG 'pub/');
define('DIR_WS_TEMPLATES'DIR_WS_INCLUDES 'templates/'); 
Have you got this section intact? - particularly the last line:

PHP Code:
define('DIR_WS_TEMPLATES'DIR_WS_INCLUDES 'templates/'); 
(NB: Yours will probably (ought to) show /shop/ in the top bits.)