Fix My PHP Quiz(repost)

Hello, Simple project. The quiz shown here: <[login to view URL]> It needs fixing the last coder, did the extra work but left a bug in the code. The quiz starts, and shows the results and the questions that the user got wrong at the end. The questions comes from a database that currently have over 400 stored, and the questions are unique and picked randomly. But when i changed the amount of questions from 10 (works good) to 50 the quiz restarts when around 30 questions has been answered. I need you to find the bug, and fix it. The quiz uses arrays and sessions. I NEED THIS FIX FAST! Use this time now to find the bug, test the quiz and when i accept you, i will give FTP access and u make the correct changes. 1 Day deadline, do not bid if u cannot complete today! Regards