Drush upwd Changes Database Hash but Login Fails
Check to see if your cookies are being set correctly. It's possible that your login is succeeding, but if the session cookie is not set, then you will be immediately logged out again (or, more to the point, the browser won't get the message about you being logged in and will continue to present an anonymous user to your site).

Check your settings.php file and see if you have any configuration options related to the cookie domain that are not correct.