I have made a comprimised version here:
Now to the problem...
After answering the first question it should (as it has always been doing) go to the next page. For most users it does, but now out of a sudden - for some users - when you click Next after the first question it jumps to end and tell that the "Last question has been answered, will you submit?". If you press OK it submits.
All the users are using MSIE 7-8. Check the code and help me...