Video of this issue soon to come-- When I start up my MB1.83, about 2-3 seconds after the mac login screen appears, the screen goes black for about a half a second to a second, and then resumes normal functionality. During the 'blackout', it continues working, it just seems like the screen is automatically adjusting its brightness all the way down to the lowest setting and then back to normal. This happens about 4/5 boot attempts, and I've even hit the power button and stepped away from the machine alltogether (I didn't know if the MB non pro has a light sensor, so I figured I should try staying away from it, with all the lights on). I haven't found any other cases like this anywhere after about 20-30 minutes of searches, so I guess it's time to ask! I cleared the pram (I figured I'd give it a shot) and the next time that I booted up there was no flicker, but every time after that the screen has gone black; that's the extent of my attempted troubleshooting thus far.