Extract all... does not work any more...

When one right-clicks on .zip files, Win XP offers an "Extract all..."
option to unpack the file. This worked perfectly until a few days ago,
but today I had to learn that for some strange reason this stopped
working on my system. If I select that option then simply nothing
happens...

Any ideas, what could cause this? Can one somehow "re-install" that
option?

Michael