Hi Jim,

Boy, do you respond fast !! Thank you.

I accidentally discovered what went wrong just twenty minutes ago. Propably
a mouse mishap. Instead of signing my macro workbook at a particular point
in time, I seem to have chosen another option of the Prrepare menu item in
the Office menu, i.e. "Mark as final", because when I hovered my mouse
pointer over the greyed-out menu items of the ribbon, that is what the
menu-comment tells me about status of this file.

So, for future (and shorter) reference: choosing "Mark as Final" is
definately a reason for Excel to gey-out all ribbon-
menu-items. It may turn out that there are even more things that could make
this happen. I tried (while writing this response I thought of trying this)
to save the same file with a different name, but that doesn't resolve the
problem.
It seems that copying the data in the file to a new file is one solution,
though it'll cost you some time. But it does seem that Final is Final.

Thank you.
Peter