My tv is a hd ready 720p resolution tv. my console wont allow me to change the setting to 720p. it only lets me play on 480p. when i plug the HDMI cable in, it says 'out of range' its not the tv because i got a new one of the same model the other day and its not the hdmi cable as it works in other peoples tvs. so i think its the xbox. any help?