Hi everyone, This is a strange problem and I just wondered if it rang any bells for anyone. By the way -- so you don't feel bad for me -- everything important on my computer is backed up. Late last night I was working on my MacBook Pro (2010, 2.53 GHz, 4 MB; recently -- in the last week or so -- updated to Mavericks from 10.6.8, if that's important). I had been using it quite heavily in the last week (trying to finish a thesis). All of a sudden, the screen started flashing rapidly. The flashes consisted of vertical lines in washed-out, pastel colors (white and pink and yellow and maybe blue). The speed of the flashes was about the same as the speed of blinking when you are feeling a little bit agitated. They (the flashes) covered the entire screen. My heart started pumping and I panicked and held down the shut down button. After praying to various higher powers, I turned it back on. I heard the boot-up noise and the keyboard lit up but the screen was totally blank. There was a noise, a low, rattling moan coming from inside, as if the computer was stuck in a coma and only barely alive. I tried to restart it a couple of times, with the same result. At that point I turned off the computer and tried, unsuccessfully, to think about something else. I thought I knew what was coming next: excuses to my advisors, existential confusion, Apple store, huge bills for parts I didn't even know existed -- you know the drill. But then the strangest thing happened. This morning while I was asleep, my wife tried turning it on and...the thing worked perfectly, as if nothing had happened. It's been blithely humming along since then, with no recurrence of last night's manic-depressive behavior. I have no idea what happened or whether it will happen again. And that's why I'm posting. I know it's a bit silly to post for a problem that solved itself, but the mystery remains unsolved. Perhaps one of you has an idea about how my perfectly ordinary MacBook Pro was seized by a temporary bout of pastel-colored madness.