Thank you, OTPM, for your help.
In fact, I have one macro of my own creation, but
- it is attached to one particular Word document only
- and the shortcut for it is CNTL+<, not CNTL+X.

In the list of Word Commands (to be seen with another option of Viewing Madros) I spot one that seems suspect, by the name of it; I mean that I might have created it unawares in the process of writing the one mentionned above; but, as is the case for all items in that list,
- its contents cannot be inspected,
- there's no way of knowing if the shortcut for it is CNTL+X,
- and, above all, there's no way of deleting it!

Anyway, thanks again for trying to help with a tip that sure seems likely.
ACA