White spots are not scanner problem but related to development process. If you scan 35mm positives on frames be sure that you choose "Type: Framed" because that makes scanner to autofocus. By default scanner is focusing on level it found best when you calibrated scanner. Also I suggest you always scan rgb and set manually white and black point. If possible you can also use some near neutral looking gray point to balance picture. Then you can do more adjusting. You should google for Oxygen manual if you are not having printed one and read at least relevant parts.