This article may helpful for some people as it generally deals with authentication issues:
http://askubuntu.com/questions/176337/installed-perfectly-but-password-not-working-for-login-or-authentication
This article may helpful for some people as it generally deals with authentication issues:
http:// askubuntu. com/questions/ 176337/ installed- perfectly- but-password- not-working- for-login- or-authenticati on