I am not able to log into stackexchange.com - specifically, this url: https://stackexchange.com/users/authenticate
I receive the message:
Unable to log in with your OpenID provider:
No OpenID endpoint found.
My OpenID endpoint is my domain, and it's working just fine, as I just created an account over at the new Electronics beta (and subsequently, asked this question to have my two existing accounts merged). I've been able to log out and back in of several different Stack Exchange sites using my domain, just not on the stackexchange.com site.
I also had my brother try and log into stackexchange.com from his work using his custom domain, and he had the same message and wasn't able to log in either.
For what it's worth, I am able to log in if I click the "MyOpenID" button (I am directed to the "hey, we don't recognize you, want to create an account?" screen).