Ever since the last security update, I have been having trouble with the text in part of a web page becoming garbled. It happens when I am scrolling through a page. I can fix it by highlighting the text and it will go away. It remains legible after I take the highlighting away. It does not happen every time I scroll, but it does happen randomly throughout the day. I have owned my Macbook for almost a year and this problem has only come up since the last security update. Has anyone else encountered this same problem?