Fortunately, I saved earlier default settings, thus in the settings dialogue you can load the old settings.
Restart Cubase 7 and MIDI works again.
For those who did not save their settings in a file the Steinberg coders and/or support might find the faulty part in the default.xml file if they can catch a breath while coding out the other faulty parts…
I go on working and hope not being annoyed by such kids illnesses.
Bye Bye 
DIY DIY DIY DIY DIY