It is at least possible
that I have found a 'workaround
' for the problem:
To resolve my own (apparently quite similar) problem described here
, I de-installed
the Perl-AddOn 1.4.12 first which means I deleted the complete content of the Perl-subdirectory, ran xampp_setup.bat again and chose "configure xampp witout mod_perl".
Then I downloaded the ActivePerl MSI installer in its 220.127.116.111 build from www.activestate.com
and installed it to the now empty Perl-subdirectory.
Result: Now the "ppm" command works and the error message is gone. It certainly took a few minutes, but maybe that's still better than to wait here for an answer that nobody really seems to be able to give ...