The same happens when I try to play GTA-IV as well. well, it runs until it gets to the Rockstar Games Social Club wherein clicking the button to play the game fails to launch the game - NO GAME RUNS. I click on the icon on my desktop or from within STEAM itself and the game says that it is running. I have a lot of computing experience for the record. Since there was not even a way to cancel this, I proceed to do so and then tried to launch EFLC again and guess what - it failed to launch.
I played about half an hour of GTA-IV then quit the game and went to play EFLC and on startup was presented with the Games For Windows LIVE box which popped up and gave me no option other than to 'remove' the application. I've loved Grand Theft Auto IV and Episodes from Liberty City (EFLC) for years and recently purchased both games from STEAM and had GTA-IV running just fine under Windows 7 until yesterday that is.