Password change
This web site authentication error really made me laugh.
I went to a reasonably high profile web site to submit a proposal. Attempting to login with OpenID challenged me to provide an email address and password (er, what was the point of asking for the OpenID then?).
Fine and dandy, except the site already knows my email address so I must have logged in last year. That means I just don't remember my password. Click on “forgotten password”. Wait. Get email. Click on “click this link to change your password.”
Provide password. Twice, per usual. Click “Change password”:

I decided to laugh instead of cry. And I decided not to embarrass the responsible parties by naming them. You owe me one.
Comments
You should submit this to Daily WTF, it's perfect for them.
It happened to me too. Awful nice of you not to name them.
Bob