I have used this troubleshooting some time ago on a Steam game:
This error results from the improper delivery of necessary game files. Please follow the steps below to initiate a small download of the missing content:
- Completely exit Steam.
- Navigate to your Steam installation folder (~C:\Program Files\Steam)
- Delete the 'appcache' folder.
- Restart your computer and attempt to launch the game through Steam
If the issue persists, it may be that a program on your machine is interfering with the proper delivery of game files:
Please temporarily uninstall any applications listed in our Programs Which May Interfere with Steam.
Additionally, it is possible that anti-virus software is reporting game files as malicious.