I had to do a complete windows reinstallation. Now I am Installing MSFS again and everything works as expected. But it is still strange. Never had such problems with any other game launcher. Anyway, Best side effect is, I have a clean Windows. 
I had to do a complete windows reinstallation. Now I am Installing MSFS again and everything works as expected. But it is still strange. Never had such problems with any other game launcher. Anyway, Best side effect is, I have a clean Windows.