I'm using Firefox 37.0 with no plugins except for a couple of themes. It's my workstation at work and the same location I accessed it from in June. I am on Win 7 64-bit. I have tried from my Win 8.1 computer at home and on Win Vista computers at school. All with the same results that I cannot log in. My home computer also has Firefox 37, but the ones at school are older I think.
I'm leaving work now. I'll answer whatever other questions you have for me tomorrow.