try changing the following code:
if(($_SERVER["REQUEST_METHOD"] == "POST") && (isset($_SERVER["HTTP_REFERER"]) && strpos(urldecode($_SERVER["HTTP_REFERER"]), urldecode($_SERVER["SERVER_NAME"].$_SERVER["PHP_SELF"])) > 0) && isset($_POST)){
to:
if (isset($_POST["Update_x"])) {
for the error, see the following thread for detail on troubleshooting:
showthread.php?t=19285