Warning: require_once(./wp-load.php) [function.require-once]: failed to open stream: No such file or directory in /var/www/wordpress/wp-app.php on line 18

Fatal error: require_once() [function.require]: Failed opening required './wp-load.php' (include_path='.:/usr/share/php:/usr/share/pear') in /var/www/wordpress/wp-app.php on line 18