Quizzes- stuck in an endless loop

I have always embedded quizzes between slides in an e-learning that are NOT graded. They are marked with the slide layers Wrong, Right, Try again and Feedback (this is always displayed so you can see the correct results). Now you can skip the quiz questions unanswered by simply pressing the next button. If you press the submit button on the feedback layer, you get into an endless loop where the quiz starts over and over again. How can I get around the problem that participants can either skip the quiz completely or get stuck forever?