Thanks for all the tips.
At present I have another woe:

I followed the instructions suggested but when I want to reinstall
(8.1.7 in this case on XP) I have one deinstallation pending (8.1.7
which I chose before on my fruitless attempt to deinstall using
the "de"installer) and the other products are not getting installed since the
installer "thinks" they are already installed.

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Chris Christoph P. U. Kukulies kukulies (at) rwth-aachen.de