I finally decided to do what many of you have suggested and re-download the game. I deleted everything except the save files and downloaded it and it did fix the glitch.
I will now be able to finish this awesome film of a game.
Thanks to everyone that responded.
It was actually lol was going to think it went unnoticed.
haha, nice, I liked it, anyway, it's fixed for you then apparently by redownloading it, so that's good
I had a friend a long time ago in Uncharted 2, he had a copy of it and on the Nepal coop map, he always fell through the floor and died at a certain point in the level, no matter who he played with, he always feel through the floor at that point, and he never could finish that coop map, maybe that glitch somehow got into The Last of Us as well, but you got lucky you could just redownload it, he wasn't so lucky