Fallout 3 Won't load!!?

ok so i bought fallout 3 in january and its been working fine until a couple weeks ago, on my main saved game, whenever i try to exit rivet city it just stays on the loading screen forever. i took the game back to get it clean and that didnt work, so i ended up getting a new copy, and it still has the problem. i dont want to start a new game because it would be a huge pain trying to get back to how far i was. PLEASE HELP!!! ALSO i have it for the 60gb playstation 3