Just got my PS3 but it wont display 1080p?

Hey peeps i just got my PS3 slim and currently updateing firmware. Anyway whilst its updating can any1 give me a reason why the PS3 wont display 1080p? Im currently at 720p that works fine but when i tried 1080p my TV gave me a dont fit message something like that anyway. I know my HDTV displays 1080p it says so on the box and i was running my xbox at 1080p so why ain't it working?

Im also using a HDMi cable im guessing i need to tweak some settings?

we need to know the brand of tv, theres a chance that perhaps youve made the mistake a lot of people make in that the tv box says can take a 1080p signal and taken that to mean it can display the signal when in actualy fact it can only display 720p and what it means is that the tv is capable of taking a signal from a 1080p source and down scalling it to 720p to fit what your tv is capable of. I dont think the ps3 will set to 1080p in these cases unlike the 360

it sounds like 2 me that youre tv isnt 1080p. check the tv manual and see what the tvs native resolution is.just because a tv sys 1080p on the back dont mean anything. it just accepts a 1080p signal and downscales 2 720p.

Also, I think a key point to point out is that nearly every PS3 game out only runs at 720p max, my TV auto-adjusts from 1080p on Blu-Ray to 720p for games.