don´t start a session here. I don´t think it´s needed. Let´s see if it breaks something

apps/files/ajax/timezone.php

 <?php
 	// FIXME: this should start a secure session if forcessl is enabled
 	// see lib/base.php for an example
-	session_start();
+	//session_start();
 	$_SESSION['timezone'] = $_GET['time'];
 ?>