User Settings Page Downloads PHP File

I've got a site that works except for one major problem: After logging in, My Account tab looks fine. Clicking on the Edit tab starts a php file download! I can't see the options that are supposed to be there. The text is below.

Thanks in advance.
Michael
<?php
// $Id: index.php,v 1.90 2006/01/27 18:51:51 dries Exp $

/**
* @file
* The PHP page that serves all page requests on a Drupal installation.
*
* The routines here dispatch control to the appropriate handler, which then
* prints the appropriate page.
*/

require_once './includes/bootstrap.inc';
drupal_bootstrap(DRUPAL_BOOTSTRAP_FULL);

$return = menu_execute_active_handler();
switch ($return) {
case MENU_NOT_FOUND:
drupal_not_found();
break;
case MENU_ACCESS_DENIED:
drupal_access_denied();
break;
case MENU_SITE_OFFLINE:
drupal_site_offline();
break;
default:
// Print any value (including an empty string) except NULL or undefined:
if (isset($return)) {
print theme('page', $return);
}
break;
}

drupal_page_footer();