Con eso me da
Warning: file_get_contents(
http://www.dominioexterno.html): failed to open stream: HTTP request failed! HTTP/1.1 403 Forbidden in /web/htdocs/www.dominiopropio.com/home/file.php on line 40
en la linea 40:
$returned_content = file_get_contents("http://www.dominioexterno.org/pagin.html")