If you are unable to log in with CAS after migrating a site, make sure you copied the .htaccess file in the root of your site (httpdocs on OIT Web Hosting).
Please note that this file may be hidden to some file browsers. If so, configure your file browser to show hidden files.
CAS requires that Clean URLs be enabled. When Clean URLs is enabled, Drupal edits the .htaccess file to properly handle normal-looking URLs.
When a Drupal website is migrated without the .htaccess file, Drupal reverts to the ugly URL schema (i.e. http://drupal.gatech.edu?q=user/login). This has the side-effect of also disallowing CAS from working properly.