Ok, just got my 360 yesterday and this is what it is doing...
Under Video options on the 360 dashboard (?) I select Widescreen and everything is fine. Now, using the component cables, i select 460p and it says "accept?" and i choose yes, and then the screen goes back and says that HDTV is disabled, TV is the selected output. It does this for every option (460p,720p,1080i) even though, after it "tests" and asks you if you want to keep the selections, it looks fine.
Is there something i am doing wrong? Even on the ps2 i could use the 460p and it would work. THanks for your help!