I just reinstalled 9.0 after a hard drive failure. It had been working fine before (Nvidia 980) and this was the first thread Google showed so I wanted to post how I fixed it to help others that encounter the problem.
I first checked all the things in the knowledge base article, but all the Aero stuff was already enabled. After reinstalling Windows, I had changed the background image and turned off Windows sounds as is my practice. On a hunch, I changed back to one of the standard Windows themes, and Cubase then came right up.
After shutting Cubase down, I then changed my background image, and turned off Windows sounds, and launched Cubase again. It came up fine.
What I take away from this is that something got refreshed by switching to a standard Windows theme, after which I could customize my desktop again without problems. Hope this helps others who encounter this.