how to fix the lighting?!?

[jens]

Well it looks like it should at first, then when the item should flashe it makes the whole screen flash instead and this in turn then makes the ambient light setting for the level break, so the game is after that "broken" and that is why it is so dark. When you move outside the area that makes the item flash, the ambient light setting is fixed again.

So the darkness you want is not meant to be in the game, but you could simulate it with by lowering the gamma setting or using the previously mentioned modification. And also to turn of the item flash in settings so that the flash wont occur.