thank you for your immediate reply!
Attached please find two screen shots taken from the displays of the appliances which will hopefully answer your question.
I wish to add that the icons of all other programs are appearing in their particular form and color. Therefore I have not assumed a basic problem but something special about PDF-Viewer which was the reason to contact this forum.
Yes, it is absolutely certain that PDF-Viewer was installed properly (more than once) and that it is connected with PDF files. And this is working fine because if I click one of those white files it is immediately opened by PDF-Viewer.
I have even checked the connection (where the files are connected to certain programs - I do not know the English term). Anyway there .pdf is connected to PDF-Viewer.
After that I have checked the complete list (standard programs) and found no mistakes - and certainly not as far as PDF-Viewer is concerned.
I did not follow your advice (...knowledge base article to find out how to re-register our shell extensions so Windows explorer can show the preview
) yet since I wanted to answer your post immediately.
We now have to leave - birthday of our son in law
Thank you again