In an answer for a MyOpenID login-related question, I find that it shut down as of 1st Feb 2014. But then why is the Data Explorer giving me the option to login using MyOpenID?
Please remove it from the login options.
I have some authentication changes for Data Explorer in the pipe that include removing the MyOpenID option, so this is status-planned. I'll try to get them out by Monday at the latest, and then give 6-8 weeks for deployment.