Tivo to Projector home theater system: picture is dark!

I have the tivo Premier Q supplied by Mediacom which is hooked up to my Sony Receiver. Also connected to the receiver is my PC and BluRay player, all HDMI. A single HDMI cable connects my receiver to the projector (Viewsonic Pro8200). Video quality when watching movies through my PC or Bluray player is great! However, watching cable movies via my tivo is horrible. Dark scenes are miserably black, with complete lack of subtle details. Daylight scenes and sports programming is OK though. Any ideas why?

I have tried different HDMI cables. Also connected Tivo to another LED TV and it looked great!