Windows client closes down repeatedly when trying to add new account

I created a new account via browser interface.
Then I try to add this account to my Windows client.
After entering the credentials in the browser and getting permit granted for the client, the client window opens for a short time but the next window does not open. Instead the client closes down without me doing anything and the symbol disappears from the taskbar. When starting the client again there is no trace of the new account I had wanted to add. I have tried several times with different browsers, always the same behaviour.

Any idea?