Is there anyway to set the brightness on the powerbook with the ambient lighting as it just seems completely random at the moment. In the dark on battery life I like it on around 4 bars and in the light around 4 bars from the top. It doesn't seem to be doing that and with the same light it shoots up and down aimlessly. I know the ambient lighting is supposed to do this to a degree but It's just being completely random at the moment and is either going too bright or too dark. Any ideas?