Giles,

            There is likely some corruption in your Windows 10 installation itself that needs to be remedied.  The probability of this being an NVDA-based issue is very small indeed, particularly if you've already tried uninstalling NVDA and reinstalling it.

My standard advice, in virtually all cases, (and presuming any potential infection has already been addressed, first) is trying the following, in the order specified.  If the issue is fixed by option one then there's no need to go further.  Stop whenever your issue is fixed:

1. Using SFC (System File Checker) and DISM (Deployment Imaging Servicing and Management) to Repair Windows 8 & 10 

2. Doing a Windows 10 Repair Install or Feature Update Using the Windows 10 ISO file

3. Doing a completely clean reinstall (options a & b are downloadable PDF files):

           a) Completely Clean Win10 (Re)install Using MCT to Download Win10 ISO File

           b) Completely Clean Win10 (Re)install Using MCT to Create a Bootable USB Drive

           c) How to do a CLEAN Installation of Windows 10  (Tom’s Hardware Forums, with screen shots)

I never choose the “thermonuclear option,” the completely clean reinstall, until it's clear that this is the only viable option. I hate having to go through all the work of reconfiguring a machine from scratch if that can reasonably and safely be avoided.

 

 

--

Brian - Windows 10 Pro, 64-Bit, Version 1903, Build 18362  

The color of truth is grey.

           ~ André Gide