I don't usually have a problem with other books, but when I am reading NA27 w App (NA27GBS), scrolling with two fingers on a TrackPad, the movement is not fluid or smooth. Specifically, the text starts to move, then stops, then moves again with a jump. How can this be addressed? I have an i5 MBP 2010 with 8gb ram and although there are other books that could scroll more smoothly, the NA27 w App is the one I've found with the biggest problem. Thank you.