Does anyone face any issue while answering/submitting exams knowledgeblackbelt.com

Every time I try submitting/answering a exam at --> http://knowledgeblackbelt.com/ I end up with a Vaadin Exception that prevents me from answering/submitting the quiz? I also had a lot of other UI problems like entire questions not showing up. The question navigation panel on the right hand side seems to only show 30 questions too, irrespective of the number of questions in the Quiz!

Is it just me or did anyone else face such a problem too?

(Tried out in FF, Chrome, IE (I got the the latest versions of the browsers) - I seem to have issue with all browsers!!)

I have noticed some problems too, the last exam I took had issues like missing questions, 5 blank radio buttons as possible answers, no possible answers...makes it quite difficult to pass!