I've spent several hours trying to fix it and have absolutely no use for autoscroll myself. Interestingly I can get it to be either group of 2 lines depending on where on the screen I was writing last. the LCDtest suite (included in the download) demos this. It of course doesn't affect smaller LCDs with only one HD44780. As far as I can tell it doesn't affect the other commands that need to go to both HD44780 chips on the 40x4--clear, home, righttoleft text mode, scrolling under program control, display on/off etc. >:(