Over the past week, my firefox screen has begun blinking. There is no rhythm to it. The first blink is generally 10-15 minutes after I open my laptop and hop online. It's a micro-second blink with nearly no interruption in the image, just a perceptible blink, almost like it's what's behind the content that's blinking. I have a macbook air, everything is updated and current. I've watched over the past 3-4 days to see if there is a pattern, and I find none other than it happens randomly when I'm online. Any thoughts?