Somehow the issue resolved itself. Suddenly MO just worked again, while it was running (previously restarting the application didn't help, and the issue arose while MO was running already for days uninterrupted). I haven't had any configuration file open in another application, am using the embedded administrator account of Windows (have been for years), so everything runs with admin privileges by default, I haven't quit another windows application to make it work, there is or was no process running I could even remotely suggest was clashing with MO. I have simply no explanation for what just happened, and that's not something that happens often.
