error msg on trying to open Cubase Pro 8

I get “DWM composition not running. Please switch to an Aero theme.” When trying to open Cubase Pro 8.

I have a brand new Gigabyte Radeon R7 250x video card with the latest drivers running dual monitors. i have selected a hideous Aero theme and “enable desktop composition” is checked and still no luck. Any ideas?

Andy B