OH... MY... GOD!!! This is the solution I have been looking for.
Robin from PDFForge... I cannot express my level of fury toward your software for the trouble this has caused. I know I'm sounding dramatic however this has cost me roughly 30hrs of troubleshooting over the last 4 days - trawling through various websites and forums chasing red-herring leads. Time that should have been spent with my family. I should have gone for a complete Windows re-install days ago... however I thought I was always one step away from a solution. As it is finally I have just spent the last 5 hours prepping my computer for reinstall (backing up user settings, transferring files etc) - before deciding to chase up 'one last lead'. In hindsight I would have been far faster to simply reinstall Windows.
Please let me explain how this problem manifested itself. First... I have a 1 year old computer, relatively good specs, running WIN10 (clean install 6months ago). WIN10 fully updated. Drivers fully updated. Not to much software installed... mostly office productivity, photo and video editing software. Zero games or potentially "compromised" software from "questionable" sources. Whole system running fast and error free. I downloaded and installed PDF Architect roughly 10 days ago (activating Creator Module with shell extensions) whilst scanning and archiving. It worked perfectly and I did not detect any changes in behaviour whilst I used my computer daily. After roughly 5 days I started noting issues (because 5 days had passed of full time use, I had absolutely no reason to suspect PDF Architect - this was my first BIG mistake) - here is now a rough sequence of events...
1. First symptom - Suddenly I could no longer access Control Panel via (Right-Click) START MENU > CONTROL PANEL. An error dialog would popup "The remote procedure call failed" and the Explorer Shell would crash and restart closing all windows.
2. Scanner TWAIN drivers vanished and scanner no longer detected. (They were obviously still there but scanner no longer detected)
3. All windows explorer shell functionality slowly degraded until until windows desktop was barely usable and was constantly crashing and resetting. "The remote procedure call failed" error dialog became more frequent. Access to Control Panel could only be made through the "run" prompt.
4. I attempted a "Restore" from a restore point. This failed. Windows restore was failing in the restore process and making no changes. Restore was not working.
5. From Elevated Command Prompt I attempted SFC /scannow. It returned with an error however the error could not be repaired.
6. Rebooting into Safe Mode obviously would stop the problem. Access to Control Panel and windows explorer worked properly (although in Safe Mode).
7. Research on "The remote procedure call failed" (my most obvious symptom) lead me to DISM /online /scanhealth and /restorehealth. Both returned errors however would not repair. (A lot of time was wasted on this area).
8. I then downloaded and mounted a WIN10 ISO image, and attempted an "in-place upgrade" of Windows 10 attempting to re-install the entire operating system whilst keeping apps and user settings and files in place. This eventually completed successfully however it did not rectify the problem. Control Panel access still resulted in "The remote procedure call failed" and explorer shell crash/restart.
9. I have uninstalled a bunch of drivers in an attempt to narrow down the problem with no success.
10. I spent 2 hours on the the chat line with Microsoft Windows tech support this morning and she remote accessed my PC, however she could find nothing, and based on my symptoms, advised a complete reinstall of windows. I finally concluded I would have to fully reinstall and spent the last few hours preparing for that... however...
11. Just prior to doing a complete reinstall I realised that I had overlooked the "event viewer". Yes... I realise I should have gone there earlier... however googling the big obvious "The remote procedure call failed" lead me down a different path. I noted the one particular error in event viewer... (pasted below) and googling it lead me to this thread. HALLELUJAH!
12. I immediately uninstalled PDF Architect... rebooted... and full system functionality has been restored.
13. Here endith my tale of woe... 4 wasted (holiday) days later. To say I'm not happy with PDF Architect for this trouble is an understatement.
The event viewer error is:
Faulting application name: explorer.exe, version: 10.0.10586.494, time stamp: 0x5775e575
Faulting module name: support.dll_unloaded, version: 126.96.36.199684, time stamp: 0x572a0944
Throughout this process I blamed viruses, then my antivirus software, then bad windows images, then corrupted system files, then a corrupted SSD - at each step scanning and testing only to find these weren't the cause. Who would have thought one small program could have caused so much mayhem.
Thank you once again Alain-Henri for your post.