the problem is that the on the index page, the recordset is set to filter based on session variables that get set on the other pages.
when you first visit the page it displays fine because the session don't exist.
on the index page, you should unset the session if the exist at line 1:
<?php
if(isset($_SESSION["passedYear"])) unset($_SESSION["passedYear"]);
if(isset($_SESSION["passedMonth"])) unset($_SESSION["passedMonth"]);
?>

