The most common reason for a course to "get stuck" or not launch (with or without and error page) is that the course was corrupted when downloaded. Fortunately this is often a simple problem to remedy. Usually closing your browser, reopening it and then clearing the browsers cache and then logging back into your training will resolve the problem.
NOTE: clearing your browsers cache frequently requires more than just clearing the history. Refer to the specific instructions for your browser for the steps to accomplish this task. Usually a quick google search like "how do i clear the cache on [insert browser name]" will do the trick.
If this does not remedy the problem please email us at email@example.com