Problem employee or problem with a good employee? You need to know the difference. Even good people make mistakes or go through rough patches.
Do you really want to lose a good person you have so much invested in and go through all the trouble of replacing them, or do you want to help them work through it?
A lot depends on the employee as well. I do not require them to submit themselves to a perilous task or dangerous exertion. That choice is completely up to them. If I do notice that they try to accomplish something extreme I usually like to be around to keep them a hand. It just makes me feel better knowing that I was by their side helping.