Search did not come up with solution so i made new thread.
I appologize if this is chewed to the end.
Played multiplayer for few minutes and BANG, infamous headbug strike.
Did not know any solutions so quitted and went to bed (to late to reconnect).
Today i tryed to start one of the missions and strange enough, the headbug was there. It followed me to the single player mission. I tryed two missions. I quitted and tryed with vobsound mod and other mission. It was still there.
Scratched my head, googled and called my mom. Nothing.
Then i started to change the settings to see if there's something to do. And strange thing happened, it got fixed with changing the antialiasing setting.
That setting was on normal and i dropped it to low and everything was ok. No headbug anymore. The guy looked over the gun and moved straight.
So, this thing fixed it for me. On 8800GTS with 182.08.
All settings "application cotrolled" except gamma ON and transparency OFF.
edit: I just add, that i did the change on the fly with only that change at the time. When i esc back to game the problem was solved.