Explorer.exe takes 13% of processor - constantly restarts

I have one machine running 15014 (for some reason it hasn't downloaded 15019 yet even though I'm on the Fast Ring) - the machine has shown this problem since 15002. Essentially explorer.exe uses 13% of the processor all the time. If I right-click on the desktop, explorer.exe restarts itself. If I click or right click on the task bar, the same thing happens.

I have done the following:

sfc /scannow - dozens of times
dism /online /cleanup-image /analyzecomponentstore
dism /online /cleanup-image /checkhealth
dism /online /cleanup-image /restorehealth
dism /online /cleanup-image /restorehealth source:wim - and pointed it to a USB drive
I have mounted an ISO image and used the source function.
I have mounted a wim image and used the source function.
I have used the Image Heath cmd that I downloaded from this forum.

I've created a new user account - it didn't help.
I've enabled the built-in administrator account - it didn't help.
I've booted in safe mode and tried repairing things - it didn't help.
I've booted into WinPE and tried repairing things - it didn't help.
I've disabled all non-MS services - it didn't help.

I have downloaded Tweaking.com's repair tool and repaired everything multiple times.

I've run the troubleshooters for Windows Update, Windows Store Apps, BITS, etc.

I've done the trick of turning off windows update, bits and crypto, renaming softwaredistribution, etc.

I have done an in-place re-install, twice.
I have done a install where I only kept my files, and allowed it to delete my apps.

Nothing has fixed the problem.

The event viewer shows a bunch of 7024, 7043, 10010's, 10016's, 7023's.

I've systematically tried every repair for every error and nothing has fixed them.


Is there anything else I can do, other than completely wiping the drive and starting over?

Thanks,

Paul

I should have added those to my list of things I've tried.

I have the SysInternals suite installed and have run both procmon and proc explorer and couldn't find anything unusual.

I've already done clean boots and it made no difference.

After doing an install where I only kept my documents, not apps, there's nothing installed in the context menus. But, yes I've disabled everything previously in the context menus.

In Process Monitor I don't see any "bad" errors, just lots of "NAME NOT FOUND" or "FILE LOCKED WITH ONLY READERS". I see a few RuntimeBroker.exe with INVALID PARAMETER, but that's about it.

I was always under the impression that an in-place upgrade would fix most problems but it doesn't seem to be the case.

Creating a new user profile didn't fix anything either.

It just seems very strange that doing a re-install and not keeping any apps still didn't fix the issue. Though since build 15002 I've had problems on more than one machine. Even my Surface Book is having trouble with things like, all my start screen tiles being dark & having exclamation marks on them.

It's one thing if I'd just downloaded and installed some new software and the problem appeared, but when problems appear after a Windows update, it's frustrating.