Sometimes when moving a Drupal directory it will not copy all the files into the new directory. This can be caused by the way you copy the files and/or the permissions of the files on the webserver. I had a Drupal site that would work perfectly in its original directory but if I copied the Drupal 7 software into another directory I would get a 500 error or the browser would go blank. It took me a while to find the .htaccess was not copying into the new directory. As soon as I manually copied it across the website worked perfectly.