Thanks for the tip.
I looked at the various pages you pointed out, and it seemed to me that none of them really corresponded to what I am doing. But I figured, what the heck, by now I am ready to try anything, so I did update to Strawberry Perl v 5.20.3 and tried again.
The result changes slightly, in the sense that now that last message the program puts in the log is :
2016/10/01-12:13:37 I process(): starting child with command [E:\MIRA\strawberry\perl\bin\perl C:/EFS/bin/MiraAdd_medfolio.pl .. renoved .. "E:\MIRA\Migration\medfolio_test\NxExport\output\Alles/FOLDER_41486093_177671_12/OVERVIEW.xml"]
and I do not see the "select:" error message anymore.
But the program stops just as dead in its tracks.
In the Windows Application Event log, the message also changed slightly, and now says :
Application Failure perl.exe 5.20.3.3 in encoding.xs.dll 0.0.0.0 at offset 000014ea
So it is no longer "encoding.dll", but instead "encoding.xs.dll".
Any other ideas/suggestions/questions ?