Cod4 ps3 issues

Having a problem w/ my sony ps3. I played call of duty 4 long enough to have almost gone around twice in online mode, that is leveling up I mean. Also played all other games, no prob. Then for no reason seemingly, the ps3 won't play either cod4 or 1 other game (MLB 2K7). But both those games play fine on any other systems I have tried them on. When I insert either of those games it just sits in a never ending load mode. I even used 2 other cod4 discs from friends and they did the same thing. Both discs are in fine shape and I have used a "gameDr" laser lens cleaner on it. Also reset & updated the system. Does anyone have a clue what is wrong here and what I could do to fix it? I would appreciate any help whatsoever, thanks in advance. I would love to play this awesome game again.