Calculator opens multiple times & files/folders delete on left-click

[Porthos]

2 hours ago, JBS-PC said:

Think I'm just going to have to resort to restoring the factory-installed OS from a fresh recovery USB

If you decide on that route I suggest t the following.

Please do a CLEAN install using the following instructions.

NOTE:

You must remove ALL partitions of the drive you're going to install Windows on
You must verify the HASH for the ISO image used

If you do not follow the directions as provided then that may be cause for issues.

DO NOT use any activation tools or programs. Windows will work just fine without activation except being able to customize the desktop, but there are workarounds for that if wanted.
DO NOT install any other software. Get Windows installed. Then come back here and let us know.

 

Clean Install Windows 10 & 11 (2023)
https://answers.microsoft.com/en-us/windows/forum/all/clean-install-windows-10-11-2023/1c426bdf-79b1-4d42-be93-17378d93e587

Also, please review the following topic

Bypass Microsoft Online Account Creation during installation of Windows 11

 

[JBS-PC]

The PC has both a C: drive (for Windows and apps) and a D: drive containing only user data files.  Should I be formatting both (D: drive is backed up externally), or is it safe enough to leave the D: drive alone?

[Porthos]

5 minutes ago, JBS-PC said:

or is it safe enough to leave the D: drive alone?

If possible I would physically disconnect the D drive before installation.

You can reconnect the drive after installation after you see if the issue is fixed.

[JBS-PC]

OK - noted 👍

[JBS-PC]

Interesting development: I brought the PC back to my place in preparation for working on it over the weekend.  Booted up into Windows, everything working normally. 

Not signed into the Microsoft account as there's no way I'm plugging that PC in to our home network!  Also discovered that there's actually only one hard drive, not two as I thought earlier.  D: drive has vanished, so I'm guessing that must have something to do with the Microsoft account / OneDrive.  Now I've got no idea what's going on 😂

[David H. Lipman]

RECAP:

What the Mouse and/or Keyboard wireless?

[JBS-PC]

Both wired

 

[David H. Lipman]

Thank You.

[JBS-PC]

Happy to report that the problem is solved.  Keeping your suggested procedure above as my last resort, I decided to go for the full Dell factory reset option with total wipe of hard drive as their version of the OS image also included all of the correct drivers for the specific PC.

Since I now believe the problem was likely linked to a compromised/corrupted Office365 account, I set up a new clean subscription to Office365 (different email account) and will simply let the old account lapse.

Everything has been working normally for a couple of days now, so I think we're back.

Just wanted to thank you for your troubleshooting advice and support throughout my 'journey'.  It was reassuring to always have something else up my sleeve to try.  You now have a new subscriber to premium Malwarebytes 🙂

Cheers
Steve