Ultimately of course I just want to scan and print on this W2K computer, and printing already does work, thanks to you. The XP laptop has insufficient memory and I cannot upgrade it beyond 1 GB.
But after having installed, scrutinized, explored and discarded NINE different HP installation packages of scanners and AIO devices (the latest one was the F440), I have come to the conclusion, that editing the registry is the simplest solution. In fact, I doubt, that there is any other solution at all.
It is a question of perspective, what is complicated and what is simplified. Biased by my background of having started with MS-DOS and juggling with interrupts, to me editing the registry has always been the simplest way to fix things. And thanks to Erunt/Erdnt, there is no risk. Blind trial and error with one near miss after the other seems more complicated and more frustrating.
So of course I follow gratefully every lead to get that scanner working, no matter how. I am stuck, as merely knowing, where the problem is in the registry, does not get me any further, because as much as I have googled, this information is nowhere to be found. I feel like someone attempting to repair something, but lacking a crucial spare part.