Screen fades to black but the game continues

[DuckOfDoomSAF]

I have a bizzare issue with the game thats driving me nuts. In some areas, the screen fades to black as if the GPU isnt sending any signal to the monitor. The weirdest thing is that this isnt a crash - if I hit the inventory key, lantern key or esc the screen will redraw correctly. This does not happen near light sources or if I have a lantern out. Here is some information:

- This is a steam copy of Amnesia, thus I assume its fully patched.
- My graphics card is ATI Radeon HD 4550
- Drivers are up to date, I attempted the latest update to resolve the issue earlier
- Power settings on both the monitor firmware and PC settings are set to never switch off the screen
- This issue seems to only occur in fullscreen mode, windowed mode appears to run fine.
- Tried all in-game settings, ran the game barebones etc - this issue does not seem to be specific to any graphical option in-game.

I am pretty sure I have narrowed the issue down to the graphics card, which I know works fine in every other game I have, but I cannot narrow this down any further. Any ideas on whats causing this?

edit: Ok we established it is due to Gamma level settings. This effect does not occur at Gamma level 2.0 - naturally, this makes for a poor gameplay experience. Any ideas on how to fix it?