Near the end (I think) of chapter 12 when you climb vertically on red and yellow pipes, hiding behind boxes and shooting bad guys, at the top you swing across pipes. On the last one, a guy appears and when I try to swing across I look like I hit an invisible wall and fall down. Is this a glitch? I watched a youtube walkthrough video and you should be able to swing across but I keep falling to my death. Help!
I think you're talking about the part at 26:47 of this video:
If so, it's definitely a glitch. You should just be able to jump from the last pipe and kick the guy off the platform. It could be that you are bouncing off the guy because you didn't hit punch (square) in mid-air before coming into contact with him, or maybe because you hung out on the pipe too long before jumping.
Have you tried saving & quitting, then restarting your PS3 and reloading? If it is a glitch that will probably fix it.