in the room where the spoiler-ific things are fighting the mercs, and its a big octagonal shaped room, rpg merc and gatling merc are in there too.
after you defeat everything, DO NOT TRY TO PICK UP ANY WEAPONS, THE GAME WILL FREEZE.
theres another topic about ps3 freezing up and for everyone its this chapter and this section only. its been narrowed down to picking up a weapon that does it. it autosaves though so you're in the next area when you load the game again but its annoying.
its not specific to any model of ps3, its all including slim. its a software error.
SBAllen and his Mustachio cowgirls http://i44.tinypic.com/11h5jl5.jpg http://i39.tinypic.com/jtnfab.jpg http://i30.tinypic.com/15g7zmv.jpg
I imagine this is just a spot that overly stresses the GPU and some PS3s that are operating at the edge...be it not ventilated the best they could be or simply getting a little hotter than normal lock up...most people likely don't have a problem at this point...otherwise they would have found the problem during testing.