NEVER double-click on the quiz link or on buttons on any other screen. Always just click once. Blackboard understands each click as an attempt to take the quiz. If you double-click, Blackboard thinks you have just tried to take the quiz a second time and could, depending on how your instructor wrote the quiz, send you a "you have already accessed this exam" error message. Double-clicking can also keep you from seeing any quiz feedback your instructor might have provided.