When I open a PDF acsm file, when I use my down arrow key to scroll, it doesn't scroll smoothly; it scrolls in a broken motion and makes a noise every time I press the button. My only other option is to move the scroll bar with my mouse, but for some screwed up reason, Adobe has made it so that if I do that, it scrolls too quickly so that I lose my place. Does anyone know why I have this problem? Is it my computer or something with Adobe's software? I am using the newest OS version for Mac, but my Mac is from 2009. I have updated to Adobe Editions 3, but I still have the same problem.