I have a 5970 and experienced a ton of flickering when outside, anytime there was a lot of light on screen, and especially during smoke effects. I researched and researched a fix, from renaming the crysis 2 exe to updating to 11.4 preview drivers, and tried a thousand different graphics settings.
Then I just disabled the fullscreen option, and BLAM. Fixed. I don't know that this particular setting will help others, but it certainly fixed it for me.
WOW! Thanks for this ground breaking research you put into this problem, I know it must of took tens of hours, if not days to research this solution! We'd be lost without people like you, BLESS YOU KIND SIR FOR ALL OF YOUR WISDOM!