I'm getting a really weird graphics issue everywhere in this game, and I can't find anyone who has had the same issue. The colour channels seem to separate, creating a sort of "rainbow effect" on every 3D scene, as seen in the pictures (sorry they're blurry, but they get the issue across).

This is really annoying and washes out the entire screen so that all detail is lost.

This computer is an older one, with a Core 2 Quad CPU and a GeForce 8800GT, but I've not had issues with other fairly new games like the Telltale Monkey Island series or Brothers: A Tale of Two Sons.

No amount of faffing about in the GPU control panel or with the game settings seems to fix this. Does anyone have any idea what to do?

I don't have this game, but it looks like you've enabled a stereoscopic 3D mode which needs red/blue glasses to view (which filter the separate images intended for each eye).

I know this is not the case, since the colours are split into three, not two. Also, there is no such setting in the game.