After replaying Chapter 15 probably 3 times and countless system reboots, I finally got it to work. All I had to do was load up a game and play for like 2 minutes then I loaded up my original game save and it worked fine. Ironically, the game I loaded up was the Uncharted 2 demo, LOL.
Late to the party, but it's freezing on me and not letting me progress past chapter 15. I'm running a slim 250GB PS3 firmware 3.30. It keeps freezing right after the last firefight and you meet back up with Sully and the chick. If I try to load the most recent autosave it freezes during the load. If I start a new game from the beginning of Chapter 15 it freezes at that same exact spot.
I'm going to try the "play another game" method and see if that does anything, but I'm not hopeful. Also, I bought the game new, greatest hits eddition. And also got a used non-greatest hits, and tried that. Both discs have the problem.