Thanks very much for the reply. I started digging in and came up with the following php code that causes the problem. This code was in upload.php, part of an AJAX uploader that someone coded for me.
<?php
define( '_JEXEC', 1 );
define('JPATH_BASE', dirname(__FILE__) );
define( 'DS', DIRECTORY_SEPARATOR );
require_once ( JPATH_BASE .DS.'includes'.DS.'defines.php' );
require_once ( JPATH_BASE .DS.'includes'.DS.'framework.php' );
// CREATE THE APPLICATION
$mainframe =& JFactory::getApplication('site');
// INITIALISE THE APPLICATION
$mainframe->initialise();
JPluginHelper::importPlugin('system');
// trigger the onAfterInitialise events
$mainframe->triggerEvent('onAfterInitialise');
// ROUTE THE APPLICATION
$mainframe->route();
?>
It looks like the $mainframe->route() call is what causes the problem. When running this code from a file (test.php) with SEF Advance on, I get pushed to the home page. With SEF Advance off, I get a blank page that stays at test.php in the address bar.
Can you give me some insight as to what is happening? It is definately something with SEF Advance and unfortunately my php skills are only mediocre. I guess the route() is sending the page to SEF Advance? Can I tell SEF Advance to ignore this page?
Thanks very much.