Hhmm... Could be a number of different problems, depending on your set up. First and most obvious, is your TV on the right input i.e. Input 1, HDMI, component 1, etc? Do you have your xbox 360 first go into a surround sound box or anything else like that (my set up is that my xbox is plugged into my surround sound then I ran a just the yellow cable to an input on the tv)? Did it just start doing this or has it done this before? Do you get the RRoD?