lock screen and task bar glitchy

Hi!

I installed el capitan on my skylake laptop and it works really nice, graphics acceleration with the intel hd graphics 530, all the animations work perfectly but for some reason, the left side of the task bar is completely glitched out and displays all sorts of colours, one time, the apple logo is green the other time blue or red or whatever.

This also happens on the lock screen, the lock screen back and login buttons are either black or show a weird pattern.

I have attached some...

lock screen and task bar glitchy