My best guess is that something is corrupted during the download process, which in-turn cascades through and pollutes a number of consequential files.
What I have done, with some degree of success is.....
Empty the entire contents of the software distribution folder (everything, all subfolders and files).
In order to do this, you will need to stop both the Windows Update Services as well as the Cryptographic Service.
If you still have a Windows.old folder get rid of that as well.
You can do that relatively quickly by using an admin command prompt and typing
cleanmgr /sageset:1
hit enter and check every box
then type
cleanmgr /sagerun:1
hit enter and let it run