I agree, you have too many conflicting light sources overlapping. That's what is causing some of your shadows to be lightened up. You can also try reducing the angular and range falloff of some of the lights. Personally I almost never use shadow buffer, the shadows are too vague for my taste. Soft raytraced shadows can take longer, but not so much on interiors where the light radius can be set fairly low, but you have more control. I think you should try varying the strength of different lights, too.