Need to reset the resolution.
To reset the display settings of the Xbox 360 console to the default settings, follow these steps:
1. Remove any discs from the disc tray.
2. Turn the console off.
3. Turn the console on.
Note If you are using an Xbox 360 Wireless Controller, turn the console on by using the Xbox Guide button on the controller.
Note Make sure that you use the player 1 controller when you do this. The player 1 controller is the controller where the upper-left quadrant light is on.
4. As the console starts, press and hold the Y button, and then pull the right trigger at the same time. This causes the Xbox Dashboard to reset the display settings to the default settings and then automatically restarts the console. So itís OK when the Xbox 360 console restarts.
I did exactly as you said and it's working, thank you very much