This seems to be an error with Telligent.com, not sure if it is also a general error in Telligent Community 5.0?
1) Request your password at the EmailForgottenPassword.aspx page.
2) Receive an email. When you get the email with a link to reset your password, clicking the link takes you to the login page on Telligent.com. There is no place to reset your password. It just tries to make you login.