Hi Ermanno,
I don't have Vista, so I have to go with the experience of the one who have
one.
One of the work around is provided by the user “cbk0111â€
This is what he (she) have to said...
I turned off the windows automatic update and unchecked options under
recommended updates. (control panel - windows update - change settings). Then
I checked for updates - and there were some. I installed them and then ran
the windows defender update and it worked. Don't forget to turn back on
automatic updating when you are done!
Please let us know if this work for you.
Good luck
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