a que puede deberse, aqui el ejemplo de un link
http://www.software-p2p.com/descargar/
Código PHP:
$tb_sql = mysql_query("SELECT post_id FROM wp_dm_downloads WHERE id= '".$id."'");
$tb=mysql_fetch_array($tb_sql);
$post_id=$tb["post_id"];
$links = mysql_query("SELECT guid FROM wp_posts WHERE id= '".$post_id."'");
$link1=mysql_fetch_array($links);
$link=$link1["guid"];
header("HTTP/1.1 301 Moved Permanently");
header("Location: " .$link);
exit();
} else {
header("HTTP/1.1 301 Moved Permanently");
header("Location: http://www.software-p2p.com/windows");
exit();