Well, I solved it myself... If anyone gets this very problem, all you have to do is to open MiniMg V as VST plugin, open the audio config dialog and readjust the settings there. Then the standalone version will work as well.
Problem was, I already changed the audio settings to ASIO, even before I re-installed them. This seems to be stored in registry, so when I started MiniMg V again, the setting did not fit the environment any more.