OneCare in recent versions incorporated Defender's antispyware
directly--i.e. it supplants it. I haven't seen this on Vista so I'm not
sure what the behavior looks like on Vista.
I've not seen this issue on Vista, but I can imagine things that you might
try without too much effort or risk:
I'll apologize in advance by mentioning that the only Vista machine I have
available at the moment isn't running Windows Defender, so I can't test my
thinking directly. I should have some more Vista machines available within
the next few months.
I would suggest removing the definitions back to 1.0.0, and then updating
again.
at an elevated cmd prompt (right click "command prompt" and choose to run
elevated and click to agree to do that. If you are running as a limited
user, run as administrator.
Then \program files\window defender\mpcmdrun -RemoveDefinitions -All
If this succeeds, go to Microsoft Update and apply whatever is offered.
As I say--I'm not able to easily test this on Vista at the moment---so let
me know if this just plain isn't possible, but I think it will be.
Can you say more about the circumstances--just when does this error get
displayed?
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