can’t login to admin after adding keys to wp_config

Upgraded my WP install from 2.65 to 2.7 and, following the instructions in the “Upgrade Instructions Extended” added the following lines to my wp_config.php file: (NOTE: I replaced the generated keys with “====”)

define(‘AUTH_KEY’, ‘ ==== ‘);
define(‘SECURE_AUTH_KEY’, ‘ ==== ‘);
define(‘LOGGED_IN_KEY’, ‘ ==== ‘);
define(‘NONCE_KEY’, ‘ ==== ‘);

After clearing the cache in firefox and restarting it, I can’t login to my Dashboard. I get the message “Do not have permission to access this page” and I’m done. The blog displays correctly otherwise. When I comment out the above lines and ftp it back up, then I can login.

Just what exactly are these keys for? If I need them, how can I make it work? Thanks in advance for your help.