This is how I "view" what's happening. I'm not at all sure it is
technically accurate, but as a world view, it seems to allow me to get along
OK.
I believe that the current update is incompletely installed. Neither
Windows Update nor AutoUpdate see it as complete, and thus continue to offer
it.
The fix is to remove what is now (incompletely) in place.
I can imagine at least 3 ways to do that.
The standard two are:
1) KB article 915105.
2) Using Windows Installer Cleanup tool, remove: Windows Defender
Signatures.
3) (not yet tested)--using System Restore. A new restore point is set up
for each Signature installation--it is labelled: "Software Distribution
Service 2.0."
Once the current incomplete install is removed, attempt updating via both
Windows Update and AutoUpdate. At this point the update should complete
properly--it is interesting to note that it appears that this does always
succeed.
The issue can come back on a succeeding update, however.
As I say--I'm not at all sure this is a technically accurate view of what is
happening, but as a working hypothesis, the actions suggested (at least 1
and 2) seem to take care of it--so that's how I'm continuing to view it for
the time being.
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