Just in case anyone missed it. As it caused me 4 hours of hair pulling

<?php
//use constant MY_URL so no one includes $their_url
define('MY_URL', 'http://mysite.com/forumpath/');
@curl_exec(@curl_init(MY_URL."extern.php?action=active&show=10"));
?>

My guess is they just upgraded to PHP 5.2.0 which disables allow_url_include by default