Okay, so well...

Whenever I get to the end of Chapter 3 "Heat" Part D (The part with the scaffolding  and 2 giant cranes) my game starts loading then all of a sudden brings me back to the main menu. Now I don't know what the hell happened. I've deleted the game data folder and even restarted the whole game over again and still nothing works! Does anyone know what to do?

I've never heard of that problem. I haven't bought the game yet so I don't know if it's with all the cds. Check the official site's forums, and check if your disk isnt smudged or scratched, that might be the problem.
Hope that helps.

at the first part it just goes in slow motion after 18-19 seconds and i can't jump i can barely punch help me:|