Sometimes the following situation appears:

I can open successfully files with a certain extension in a program.
But when I want to go the other way round and want to open the same file (with the same program)
in WinExplorer by double clicking this does not work.

For example I installed Acrobat Reader on an USB stick and can open *.pdf files from inside Reader.
On the other hand double clicking on the *.pdf does not open it in AcrobatReader.

As a first solution I right click on an pdf doc, then select "Open with", then "Choose Program"
(remember Reader is not listed because it was installed on another computer), then I selected
"AcroRd32.exe" from the USB Stick drive and hit OK.

Much to my surprise AcrobatReader is still NOT listed as (possible) target software for *.pdf
extensions. Why?

How do I re-assign an extension *.xxx to a program without re-installing the program on the
second computer again ? This must work somehow. I have seen it somewhere.

BTW: This does NOT work through WinExplorer->Tools->FolderOptions->FileTypes either.

Eugen