I have been using Apple computers running MAMP to do my PHP web design and never had a problem with include files, I have had to start using PC and running XAMPP When I am running an require_once("inc/config.php"); on the main index.php file everything works fine, but when I go up the tree into the next folder and use require_once("../inc/config.php"); it gives me an error. can someone help me with this? This applies to when I am adding include(ROOT_PATH . "inc/_dochead.php"); on any page but the main page.