a message shows HDCP

I just bought a new appleTV. Everything works great until I attempt to play HD videos (i.e. espn now, TWC videos and also VEVO). It reads "this content requires HDCP for playback" and I've tried other HDMI cables (so it's not the cables). I'm thinking it's my 3 year old LG tv (42LH30). Can anyone help me with this issue? Thanks!