Thanks for your patience and your continuing advice.
The steps 1 to 6 that you list in your response are the same things that I did before my last email to you in order to delete all instances of HPPSDr.exe on my computer. Nevertheless, I tried it all again, but I still experienced teh same problem.
You say I should "install" Print and Scan Doctor. I am not entirely sure what you expect to happen. On my Windows 10 system, if I start with no copies of HPPSdr.exe on my system, download it from your FTP site into my Downloads folder, then "Open" or "Run as Administrator", before running it puts a copy of itself into C:\Program Files (x86)\HP\Diagnostics\PSDR, together with an icon file PSdr.ico. It also puts a shortcut icon onto the desktop (although a default microsoft icon, not its own). However, it does NOT subsequently appear as an installed programme in Control Panel>Programs and Features. Not does it put an entry into the start menu (at least, I cannot find it).
Whether on the initial run whch does that "installation" or subsequent runs from the shortcut on the desktop, the outcome is the same - it always stops at the step "Windows (WIA) Scan"
There is one thing I have observed. I have only one physical printer connected (via wireless), namely my HP Envy 5646.
This is set as my deault printer and has the name "HP Envy 5640 Series (Network)" when it appears in Control Panel>Printers and Devices, or in the list of printers available within applications (e.g. in Microsoft Word) or in PSDR. In addition I have a number of virtual printers including HP ePrint, Microsoft PDF writer, Send to OneNote, etc. When I run PSDR , then at "Choose your product" its shows three printers:
1. HP Envy 5640 Series (Network) 192.168.1.89
2. HP ePrint
3. HP Envy 5640 Series (NET) 192.168.1.67
Number 1 is the one I have been checking. PSDR communicates with it, but fails to complete the scan checking as I have said. If I choose 2 or 3 its says that it cannot communicate with them. which is not surprising. I think number 3 is somehow left over from a previous installation of the printer software etc - it does not appear in Control Panel>Printers and Drivers or in the list of printers in any application, only in PSDR. Could this "ghost" printer be causing the problem? How can I remove it?
Sorry for the continued correspondence. I am happy that I can print and scan ok, but a little disappointed that your diagnostic tool does not run successfully. Any other suggestions, or shall we give up?