Thank you Christian,
no, it is not the Minkowski.tdf, which is working fine.
I was trying to make "Hickson group"-tdf, with data (a catalogue) I took from the internet. And I now believe that the problem is a special formatting of these data from the internet, which was (or not) removed, when I sorted the data in excel and saved them (through csv) as a txt file.
Thanks a lot, (also for the hint with the registry cleaner). I will try again tomorrow, tonight I have enough !
Regards