Horrible graphics bug

[SSEAlexander]

So,i wanted to play penumbra overture along with my friend.(not multiplayer.guide him if he wants to) but he had a horrible graphics bug.
Everything in the game is just white-ish.
And a fact :
The Penumbra Black Plague worked perfectly for him.But both Overture and that...puzzle penumbra game idk what its called,are having that bugged graphics below.





His Computer is Windows 8.
His Specs are :

Windows 8.0 64bit
4GB RAM
2.5GHz
I3 Procesor

PS :
the texture bug happens only if he uses glowstick/flashlight.In the dark,textures are fine.not white.