Another blank screen troubleshooting tip per torgosPizza on ubercart.org:
"... to troubleshoot your white screen problem, put this into the top of your index.php:


error_reporting(E_ALL);
ini_set('display_errors', TRUE);
ini_set('display_startup_errors', TRUE);


That'll show you any fatal errors (which Drupal chokes on). It's helped me tons."

I think this is a wonderful tip, so I am sharing it here.