Just a weird one: when I click to run Far Cry there is activity for a few seconds, then nothing else happens, however long I leave it. If I click to run it a second time it then runs immediately with no problems. Win7 Pro.

I'm guessing it may be tied to some "punkbuster" software that failed to install because it was flagged up as spyware (I'm surprised GOG haven't patched that out).