Windows 10 couldn't be installed

Wife's Win7 computer has a strange issue with windows update. This computer never had the windows 10 upgrade as she did not want it. Have not paid any attention to windows update for the last two years or so. Decided the other day to clean up the hard drive so I checked to see if updates were current. When I opened windows update, an error was displayed, C1900101-20003 stating "Windows 10 couldn't be installed" Failed 1 update. I can manually check for updates and the message disappears until I reboot the computer. The first opening of windows update after a reboot displays the message. As long as the computer stays on, the message does not appear again until a reboot.

I have pretty much gone thru every thing I could find but nothing has worked. Apparently it is not causing any issues. Has anyone else had the privilege of experiencing this? Every incident I can find of the message has usually been resolved with simple measures - not this one! Possessed computer!
Ron

Just found the solution! Four days of this mess and for some reason, never seen this one!

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\OSUpgrade\Rollback

Delete "Rollback"

You probably have all Win 10 installation files on a hidden folder.
Run disk cleanup and select all items.
Delete Windows update files to regain hard-drive space - CNET

Megahertz07, no hidden files as disk cleanup is a routine task I always run. I even tried the handful of downloads that would fix the issue, all to no avail. Deleting the rollback key worked like a charm!

I suggest that you download and run GWX Control Panel, and let it purge all Windows 10 files from your system. And set it to actively monitor your system and block any future attempt to install Windows 10 on your system.

http://ultimateoutsider.com/downloads/

Everyone will tell you that the GWX campaign (Microsoft pushing Windows 10 to your computer) is over. But I worked on a computer about six months ago which tried to install Windows 10 when I powered it on. And you yourself have seen it as well. It won't hurt to put GWX Control Panel on your computer, and it just might protect you from a future attempt by Microsoft to install Windows 10 on your computer.

mrjimphelps, gwx was the first program I tried and it found nothing associated with windows 10 and said the computer appeared to be safe. Unknown as to why it did not find the rollback key in the registry.