Hey! HDTV/ps3 help! Would be very appreciated!?

My samsung plasma HD 720 tv use to play amazing on my ps3. Then about 8 mounths ago my freind pulled the HDMI cable out of the tv and plugged it back in (While the ps3 system was turned on) and now it looks like total **** now like 480i. And it looks like only when you run games on it! I have tryed EVERYTHING! Except buying new HDMI cable. Could it be the HDMI cable? (gold platted) But the hdmi cable works great with my 360! Any help? lolz