Sometimes in the middle of a course it freezes or a course will just not launch. Here is a trick that can help troubleshoot.
With the browser window selected, press the F12 function key. This will open a debug window if your browser has this feature (most do) and your security allows (most do here as well but if running IE/Edge, your IT can lock it out). Once the debug window is open, click the Console tab. Look for errors and communicate that to your support team.