Midi key editor causes Cubase to freeze

when I double-click the track or go to Key Editor a blank white screen opens and Cubase crashes. I have to go to task manager to close it.
Any suggestions?
Using Win7 Pro 64bit on HP i5 Laptop


What Cubase version do you have, please?

I’ve sorted it now. Found this old post online and it worked!
I would suggest clearing your App Data to give 7.5 a fresh start

First, please shut down Cubase. Then go to the Start menu, All Programs, Cubase 7.5,
Cubase 7.5 User Settings Data Folder. In the top address bar, you should see “App Data (roaming) Steinberg”
Click on Steinberg at the top. This will put you in the Steinberg app data folder. Trash any Cubase or Nuendo folders
that you see there. This will trash your key commands, preferences, sound card settings, etc.
Hopefully this will also should clear up the problem you are having.
Restart Cubase. You will need to reset your audio outputs (Devices, Device Setup, VST Audio System).
If the problem persists, are you running in 32 bit or 64 bit
Chris Dobbs

Great - OK -
after restart is a new folder created „Cubase LE AI Eleements 8_64“
no problemo