I have this peculiar problem, my sister can't log in to the Play Game tab, the form keeps emptying and she's tried more than five times. I was disconnected when she opened the Play Game tab, but I was able to log in again and then she started having trouble logging in.
I use Chrome, she uses FireFox, she tried Chrome but it still didn't let her log in, then I tried Firefox as she tried Chrome but that didn't work either, but I was able to log in both times.