Warning: require_once(__DIR__/wp-load.php) [function.require-once]: failed to open stream: No such file or directory in /wp-blog-header.php on line 13

Fatal error: require_once() [function.require]: Failed opening required '__DIR__/wp-load.php' (include_path='.:/:/usr/local/php5/lib/pear') in /wp-blog-header.php on line 13