Firts, I sory the Admin and Reader because my english very bad.>.<
When I enter Crysis 2 that show one Table with write" Unsupport this Grapid Card and you will be Crash in game" and then I log in Game with Signer Play. After the Movie to show the "Crysis 2" I was Crash game.

I just update Driver of my Garpid Card in nVidia site with version 270.61
That may PC:
Chip: Core 2 Duel 3.0Ghz
Ram: 4G
Grapic card: nVidian 8400GS
I use Windown 7

Thats because your graphics card is not supported, even if you could get it running it would look like a slide show

But with my Friend is used the Grapid Card with 256Mb he can play it.
But 8400GS is 512MB.

Still, the card he's using might be supported but your one is not. The 8400 GS is not common anyway, and it's weak. Time to upgrade.

I did find this so there may be hope for you yet

your graphic card is bad. thats it.