Hi Sergej,
unfortuenatly I’m not able to open the help file from the uSimmics installed directory directly.
As I’m not involved in the application development, its hard for me to give you a profound advice.
As you have the same problem with QucsStudio 4.3.1 the only guess I have is that it is user folder related.
In the start.bat file it is documented how you can specify another user folder.
Without warranty: Maybe you delete the .qucs folder in your homepath? For details see also the start.bat.
Good luck!
Daniel.