Try re-downloading the Security Update. Sometimes the updates downloaded are corrupt and does not install properly. Try following the steps below and then try to check for updates afterwards. This should prompt Windows Update to redownload whatever update is available that is not already installed on your computer.
Stop the Automatic Updates service.
Delete the Windows\SoftwareDistribution folder.
Restart the Automatic Updates service.
It's also best to restart your computer first after following these steps. Let us know if it works.
If you can't delete the Software Distribution Folder after stopping the services you can try and delete them on Safe Mode where all of these services are stopped by default. Just restart back to normal mode afterwards.
Nothing has worked so far.
Also tried out Microsoft suggestions.
According to the support site I am not by any means
the only one with this problem on that particular update.
Am still following suggestions on the Microsoft site and will let
you know if they come to anything.
For the benefit of anyone else who runs into this problem
I got there by viewing the installed updates, then by uninstalling
the relevant update and downloading it again.
Everything is up to date now and I thank you for all your help
I hope that anyone else who encounters this problem finds this post
Again, many thanks.