I tried a combination of suggestions and here is what worked for me. 1) I deleted my history and cookies in my browser. 2) I am using two screens, when I moved (drag with mouse) the blank login form one screen to the other, the login and password showed up. But when I typed in the user name nothing showed up in the form in the box until I dragged it to my other screen. So for each input to register (or for me to see it) I had to drag the pop-up box back and forth between my two screens. Very odd but worked.
