WELL....I thought I knew what I was doing.
In getting ready for our trip to Colorado, I wanted to check and see if there were any updates for the Magellan RoadMate we use when traveling. Since the Magellan Account Manager software is on the Windoze PC I use for all my Ham Radio stuff, I fired it up and proceeded to do all the updates that come with leaving a Windoze PC turned off for more than a few days.
Update MalwareBytes? Check!
Update AVG Free Antivirus? Check!
Update Adobe Acrobat Reader? Check!
Windoze Update? Uh-oh...there's the little "Get Windows 10!" icon in the task bar. Hmm...thought I got rid of that?
So, I "Search Installed Updates" for KB3035583 update, find it (I must have forgotten to hide it before), and uninstall it.
It requires a reboot, and then the fun starts.....
The PC goes through POST, Windows starts, then immediately goes to the Windows Error Recovery screen, and fails with an 0xc00000e9 "An unexpected I/O error has occurred" error, indicating that Windoze can't "reliably communicate" with the hard disk......
Since we're leaving tomorrow morning at 0500, this will have to wait until our return.
I used the laptop I'm taking with me to check the RoadMate for any updates, and there were none, so this whole exercise was moot.