3D glitching in demo of Penumbra: Overture

[stickynote427]

I downloaded the Penumbra: Overture demo today, and I really enjoyed playing it. The developers have done a fantastic job and the gameplay is very unique; this has also been the first time in a while that I have been frightened by a game, even considering that I only played the demo.

I am highly considering purchasing the whole Penumbra series, but one thing that makes me hesitant is 3D glitching that I experienced during gameplay.

It first started right when I began the game, on the boat. The barrel seemed to be protruding out and was stretched. The same thing also happens when I'm in the area where the metal rod is placed and the mechanism can be turned. In the tunnels, some triangles appear to be missing sometimes or I can see through the wall leading in to the tunnels.

EDIT: I downloaded the second demo as well, and this glitching occurs there, too. Sometimes it becomes difficult to play the games.

Has anyone else experienced these glitches, and do they occur in the full version as well?

Thanks.