So basically I downloaded the latest public Beta of El Capitan yesterday night.
Then this morning I started Parallels to run my Bloomberg application but the moment I start Windows 7 it starts to flicker in strong purple/pink and I have full functionality but cannot really see much on the screen. I just tried to do a screencast and take some screenshots but somehow when I try to do this the problem doesn't show in the same way.
Something to add is that I think it seems to be related to movement from other the screen or the mouse that causes these sharp purples to appear.