PS3 resolution versus tv resolution

Hello,


I have a phillipps HD 52 inch monitor tv that is set somehow to 1080i. Works great with my PS3 1080 resolution games, great picture! However, some PS3 games like GRID which I just bought only supports 720 or 780 I think. When I try to play this game, the tv signal is jammed, wrong resolution I know. So I change the PS3 res to the 720 setting and it doesn't work. My tv supports all these resolutions, do I need to manually change the tv res to run with the PS3 new res setting? To me i think this should adjust automatically anytime you pop a game in?? I could try changing the tv's resolution to 720 but I dont know how to, nothing on the menu to lower the resolution. But why should I have to do all this leg work to play a game?? Is there a setting for the PS3 to auto adjust? Even if so it seems my tv is stuck on outputting the 1080i. I am confused on what to do. I have tried changing the PS3 res and nothing works. What is weird is that I have HD cable with mostly HD1080 res stations, and also some lower end channels that aren't fully 1080 but probably much lower resolution, the tv shows the picture fine on every channel as if it adjusts itself. I have another newer and much smaller tv that is 1080i and you can easily toggle the res with no prob, it works great on this tv, but isnt my primary game tv. This is what leads me to believe its the setting on the tv?? Please Help !