Same thing happened to me.
Use internet explorer. After it takes you to the assessment fee again (you will get an e-mail saying your fee went through, dont worry, they WONT re-withdrawl from you account) your internet explorer will pop up with a "Yes or No" type choice. Click No (I think). I kept clicking yes and my session would no move forward. I believe that's where the problem is. Try that and see if it works.