I did a system restore on my PC today. I just took it back a couple weeks and at that time Unity was working properly. But since Ive done that today when I try to turn my sons game on it starts to load and then stops and either says “Unity player has crashed” or “this content has stopped because a fatal content error has been detected”. We have been playing this same game with unity for almost a year and have never had a problem like this. Can anyone tell me how to fix this? 
We published a security update recently which might be related.
What game did you try? What browser, operating system, graphics card do you have?