Redirect to Home Page When Previewing Products in Admin

[numinix]

A couple of our clients using Zen Cart 1.5.1 have reported that occasionally, when editing products, they will go to click the "Preview" button and end up getting redirected to their admin index page and all of the work they did on that product will be lost.

The only code I can find is related to the securityToken which could be an issue related to handling of sessions. Has anyone else noticed this bug?

Code from /YOUR_ADMIN/includes/init_includes/init_sessions.php:

// lets start our session
  zen_session_start();
  $session_started = true;

if (! isset ( $_SESSION ['securityToken'] ))
{
  $_SESSION ['securityToken'] = md5 ( uniqid ( rand (), true ) );
}
if ((isset ( $_GET ['action'] ) || isset($_POST['action']) ) && $_SERVER['REQUEST_METHOD'] == 'POST')
{
  if ((! isset ( $_SESSION ['securityToken'] ) || ! isset ( $_POST ['securityToken'] )) || ($_SESSION ['securityToken'] !== $_POST ['securityToken']))
  {
    zen_redirect ( zen_href_link ( FILENAME_DEFAULT, '', 'SSL' ) );
  }
}