Potentially **DANGEROUS** bug in 5.0 - 5.1

[Remington L.]

I have a Sony VAIO GRX-570 laptop. When 5.0-R came out I noticed VERY
unusual symptoms on startx. This is very hard to describe(I'm gonna get a
picture and post). When I launch startx the screen goes blank, and imagine
this ocean wave type thing sweep across my screen. Its not like just some a
screensaver, you can tell by looking at it that its not good. The symptom
lasts about 4 seconds and then it stops, and my system is frozen, no error,
no kernel panic. This also happens in 5.1, but NOT in 4.8

As I said its very hard to describe, I will attempt to grab a picture and
Ill repost. What should I do about this bug?