Without more info like your specs and such as that helping you is really a shot in the dark.
You say you acquired FEAR2 through STEAM, could the download have gotten corrupted by a power surge or spike possibly?
I would suggest going through STEAMs support and informing them of whats happening, I also have FEAR2 but bought the installation disk and the STEAM package was tied to it.
Since you bought the game through STEAM they are well aware you haven't played it yet, so they should be falling over to help you out, you'll probably have to uninstall and reinstall to solve this, Possibly.