That last survey seemed to time out if you didn't writer very short answers, or took any time at all thinking about your answer.
What I did when it froze was to exit, then go back in the e-mail and click the link to the survey. It would bring up the last question and let you advance. It is acting like there is some sort of security software running in the background that times you out if you take too long on a question. I have seen on line job applications with the same properties.