Wasn't this already addressed by QT in
http://bt.x-cart.com/view.php?id=43030
See the extra patch added there.
Basically you need to add to top.inc.php:
# If register_long_arrays = off (php5)
if (empty($HTTP_SERVER_VARS)) {
$HTTP_SERVER_VARS = (array)$_SERVER;
$HTTP_GET_VARS = (array)$_GET;
$HTTP_POST_VARS = (array)$_POST;
$HTTP_COOKIE_VARS = (array)$_COOKIE;
$HTTP_POST_FILES = (array)$_FILES;
$HTTP_ENV_VARS = (array)$_ENV;
}