Well I just got my Mac Book back from apple after I sent it in to fix the track pad and discoloring. So they replaced the keyboard and trackpad. When I first booted it up a few days ago I noticed a flicker before it got to the start up screen. I have noticed that same flicker when I open my macbook from sleep. Also the screen has froze on me where I can't move the mouse so I have to restart. Just before me typing this I got a message on the screen saying I have to restart my computer, just out of random. So my question is did apple screw up my computer while fixing it? Should I call and send it in again? Thank you.