Watched the first 2 or 3 videos,but i had a problem submitting my answers.It would reject my answer and fail to move to the next section of the lecture while at

Watched the first 2 or 3 videos,but i had a problem submitting my answers.It would reject my answer and fail to move to the next section of the lecture while at the same time not allowing me to click on either the hints or solutions tab.I was frustrated enough to logout.