I had to repair my install of Crysis through the Add/Remove Programs tool and relocate my edited CVAR folder (used to get some of the DX10 effects under DX9) before this worked. Prior to that, it kept wanting me to insert the DVD, which I already had. I'm glad this worked, because if it'd come to reinstalling the game I would've probably uninstalled and just forgotten about it. I don't have DT or any virtual drive software installed right now.
I installed the ForceWare 169.44 drivers released by nvidida today after the 1.2 patching was completed. All my config settings, such as controls and HUD color, were reset. Save games have loaded fine so far. Haven't tried multiplayer.