Richard wants to play content on his TV from his computer. But all he can see on his TV is the wallpaper. The TV screen will go black if he tries to play a movie. Leo says that's likely HDCP copy protection. Everything in the chain has to be HDCP compliant including TV, Cable, and the computer. So there's probably something in his chain that isn't.
It could also be a display issue. Richard should go into his settings and make sure that Mirroring is enabled, and make sure his display isn't extended. If he still gets a black screen, then it's a copy protection issue.