Russian Sniper

When I try to start the game sometimes it works and sometimes it will completely fail and says invalid video adapter detected. When it does work the shadows glitch out and it lags a lot. System specs: 32GB Corsair Vengeance RAM 1800 MHz Intel i7 4770K 2xGTX 770 Gigabyte 4GB Windforce OC Edition 1000 EVGA Supernove PSU Windows 8 Pro P.S: I am running the 64 bit version.