Hello. Sounds like you need to uninstall/reinstall GameGuru. You could also try verifying the integrity of the game cache. Open up the Steam interface (not the website); go to your games library. Right-click on GameGuru, and select "properties". The select "Local Files", and click on "Verify Integrity of Game Cache". Then follow the prompts.
Intel Core i7-4820K CPU @ 3.70GHz, 16GB RAM, NVIDIA GeForce GTX 770