Answer to: Turquoise vertical lines fill the white spaces on screenI had this problem with my 2011 MacBook Pro 17". It turned out to be nothing more than a loose battery connector. Luckily, I fixed it myself when I took it apart to diagnose it. The first thing I did was pull the battery connector off, and that was when I noticed it wasn't solidly attached. (They sort of snap on with a bit of a "click".) All fixed! I've seen similar things in the past. Loose connectors anywhere inside your Mac can sometimes cause weird things to happen that don't always seem to make sense. I've noticed Apple hardware is meticulously designed and constructed. (Unlike any other brand I've worked on.) Whenever something doesn't fit just right, it means you've done something wrong. NEVER force anything on a Mac. If a gentle nudge doesn't work, look for a cause of your problem. I guarantee it's there—you just have to find it!