Laptop LCD occasionally blinks

I've noticed this problem for a couple weeks now, and not sure if it's something that I should be worried about. I normally run an ext. LCD hooked up to my laptop and have both displays on. But lately Ive been using it away from home and have been noticing from time to time that the LCD will just out of nowhere blink for a quick second. It will do it once, but it could happen once a day or once an hour, so it's unpredicatable when its going to happen and whats causing it. I thought maybe it wasnt getting enough power, as I have it plugged into an ext. so tried plugging it right into the wall and another socket, but that didnt matter. Its a Sony Vaio, and this is what worries me, knowing some people have had problems with Sony screens phasing out. Not sure if thats the case with mine, and I cross my fingers it isnt, but I dont know.

And note this only seems to happen when im using the laptop LCD as the main screen. If its hooked up and ran together with an ext one it wont do it. Just few days ago, out of nowhere as I left it on idle, the screen when all grey and I had to do a hard shutdown to get it back up.

 

What video card?

 

Onboard Intel