Well...
?php
include ("root.php");
?>
needs to become
<?php
include ("root.php");
?>
unless that isn't just a cut and paste, the rest of the code looks fine, theres no ; needed in situations like that.
Try echoing the $page_header variable at different places to see where it stops working, and try putting it in a cookie to see if it can be read from that to see where its going wrong.