Oooops ! My bad !
I goofed when "manually" downloading the software from
http://calibre-ebook.com/download: I had clicked on WINDOWS and NOT on WINDOWS 64bits ! Now I corrected this and everything ran well !
Still........ why on earth didn't the software call/download the update when I clicked on "Update found: 1.44.0" ? I was indeed running a correct 64 bits version, so there must be "something" that prevented my PC to go to the download URL and do its job !!!
Any idea ?
J-P.