I have an Arduino Mega 2560 connected USB to a Windows 10 1607 14393-321 system.

The bd works fine on my laptop printing via Repetier Host. It shows up as a USB-SERIAL CH340 - ver 1607 14393-222
On my desktop it used to work with ver 8. I upgraded to 12 and now Windows won't install the driver. HOWEVER, Windows also updated since prior to my Arduino update and since the last time I used it.
I tried rolling back to Arduino ver 9 - same
I tried installing ver 8 driver, no dice
I tried driver1_CH340 and driver2_CH340
driver1 didn't work at all and driver2 came back with an error after it at least tried.
Anyone got an answer??? Is it Arduino or Windows???
How do I roll back windows to 222?? It looks like
KB3194798 is the update to uninstall.
thx