That was a good hint, didn't think of that.
In the portable copy, I chose "Help - Check for Updates", but since it is MC 13.0.62 installed, Update says there are no newer versions available.
Issue is that I had immediate MC crashes when I connected that USB drive to my laptop at work and started to play a file.
Now I have backed up a New library, transferred that to the USB drive and restored it into the portable copy. Looks like the crashes are gone.