Edited: This morning's release may fix the faulty login error; please try again with v4.0.83 when you get it?

We are working diligently to understand what's going on with this error. (You can definitely put Ghostery back; it is NOT the problem.) Some questions:

Are you using more than one Pinterest account?
Are you browsing in private mode?
Are you using container tabs?

Would you be willing to talk with me away from here to help sort this out? We have not yet been able to replicate this problem anywhere.