newbie to av need help please.

just purchased a sp4805,been messing with it for a couple weeks now.im using a m1-hdmi adapter and hdmi cable to a lgdvb418 dvd player.i cant get the projector to go any higher then 480p.ive seen some post where many have the same problems and some dont .i did install the latest firmware on the projector.and have not yet seen any loss of picture quality.any help would be great,thanks in advance.