Please try and right-click on the game in your library, go into Properties and uncheck the box "Enable the Steam Overlay while in-game". This has been reported to solve this issue.
Then try verifying the integrity of your game cache.
How to verify the cache:
* Load Steam
* From the Library section, right-click on the game 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's files - this process may take several minutes.
* Once the process is completed, the Check Window will automatically exit.
Also restart Steam after you've done this and start the game again