Metal Gear Solid 4 glitches and wont do anything after I've selected a difficulty

Hello! Ive spent hours and hours trying to figure out what's wrong with the game, but nothing has seemed to fix it. The game works and looks amazing, but as soon as I select a difficulty the game loads into a white screen. I can use buttons to change it from like white to black and stuff, but its just stuck there... Please help!!!! Ive tried everything!!!