If the number of attempts at a quiz is limited, or if there is a time limit, the student has to OK a pop-up warning before they can start an attempt.
Previously, the logic for when a warning was shown was completely broken.
I think I have fixed it, but it is a big change, so for now I have only checked it into 1.7 dev.
I would be very grateful if anyone could test starting quiz attempts in 1.7 dev, and make sure the right error is shown at the right time, and that I have not broken anything else.
Once we are sure this is working, I'll check it into 1.6+.
More info in bug 6048.
Must dash off now. Off to see Pirates of the Carribbean.