Cubase 9 not closing properly - Ctrl+Alt+Delete and end task

When I quite Cubase 9 every thing closes as expected apart from Cubase’s menu bar at the top of the screen and a gray area below that.
The only way I can close this is to press Ctrl+Alt+Delete and end task in the Task Manager.

  • Is anyone having this same issue?

How can I find out what is causing this to happen?

I project window is maximized - this is the behavior if pressing the only visible X-button, closing the project.
Cubase is running until you close on X-button again.

Is this what is happening?

Or an actual freeze?

It was freezing but last week it was working ok again. I am thinking that it might be to do with using studio manager as its synchronise window is always getting hidden behind yhe project windows.