Ok, it is NOT plugin related. I uninstalled, deleted the program folder, all folders under c:\Users\user\AppData, restarted, installed new, restartet....I see a cura icon for a half second, then.....nothing. In taskmanager a cura process is shown.
The folders in c:\Users\user\AppData are NOT created....cura seems to hang.
But where does it hang? And why?
The system log shows also nothing cura related.
But cura was running on that machine till yesterday so I think it is not a compatibility issue...