I now have 3.1.1 on the Mac and Ubuntu. Both systems still cause my my guidestar to move in a non-random almost linear direction (-3,-3) when dithering. I have it set to dither 3 pixels every three frames. But when I look at my resulting imagines (I did 30 exposures last night) every dither was 3 pixels movement to the upper left. So the whole image was off center by 30 pixels in that straight direction (up and left). I have to aligned my exposures every 30 minutes or so just to keep my target centered. While those few pixels are not huge, after a 3 hour session it is, and objects on the left side of the frame are moved off the frame.