On a BTO model 16GB, when I shut down and go to log back in and enter my password maybe 50% of the time the screen will flicker black once for a half a second or sometimes (but rarer maybe 20% of the time) it was flash a quick burst of colors, often blue, yellow, and red on a black background etc usually in a circular pattern or a lightening like formation for just a split second (so short you'd have to be looking waiting for it) I have had file vault disabled from the start. I called Apple and they said they were unaware of any issues and he said he was unsure if it was hardware or software related but told me he thought software. He advised me to wait and see if a future update fixed it or bring it in if it worsened. I haven't noticed anything whatsoever once I log in although my use is non intensive just as safari and videos. Has anyone else had this happen or care to share their thoughts?