It could be anything. It's a fatal error of some kind and the only way you'll be able to tell which error, is to add this code to the top of your index.php file:
<?php
error_reporting(E_ALL);
ini_set('display_errors', TRUE);
ini_set('display_startup_errors', TRUE);
?>After that you'll need to look at the error that shows up, and from there it'll be easier to diagnose the issue.
Joined: 08/14/2007