White Flashes not For Me

White Flashes every time, when open mixer, key editor, sample editor… etc.
Intel i7 3.60 GHz 16 Gb RAM
Win 7 64 bit.
Video AMD Radeon 7800 series with latest drivers.
WDDM - Active.

No Problems With Cubase 7.5 even without WDDM.
Still working on 7.5