I recently uninstalled FM11 via steam, then reinstalled via steam earlier today. Steam says the download was completed, but when I double click to play the message box comes up "steam is preparing to launch...." then nothing happens.
Verify your cache whilst running the game through Steam
From the My Games tab, right-click on FM2011 and select Properties from the menu.
Select the Local files tab and click the Verify integrity of game cache... button.
Steam will verify the game cache files (GCF's) - this process may take several minutes.
Once the process is completed, the Check Window will automatically exit.
Now Restart Steam and verify Game Cache again, if there are any damaged files to should re-download them now.