Graphical Issues

[rolee]

Greetings, I'm having some graphical problems which can be seen on the pictures attached. The first one in the demo happens when I get to the part when there is a corridor and suddenly it is filled with water and a monster is coming to end my misery. The second one can be found throughout the entire gameplay when encountering torches and any other light sources. It's very frustrating because I can bearly see anything because one second the flickering fire illuminates a big part of the area and when I move than it is pitch black again(sorry my english is so messed up right now and I can't really express it I hope you know what I mean from the picture).
I'm using an ATI RADEON X700 PRO on WinXP 32bit.

I thank you for your help in advance.