You can download updates of various kinds, and install them singly--but I
think the same installation mechanisms come into play in the end.
Security updates are found via
www.microsoft.com/technet/security In fact,
you can download an ISO file and burn a CD with each months security updates
on it.
You can download a Defender update either packaged via the security portal
link I posted earlier, or via the links that Engel or Tim post in the
announcements or signatures groups.
I looked at dial-a-fix, which is good for fixing this sort of issue on XP,
but it makes no mention of Vista, and I'm not sure I've ever tried to run it
on Vista.
Google dial-a-fix and look for a link to a Wiki, if you want to try it--I
suspect it will be safe to try--but it may well not help.
Hmm--permissions issues--I think there's a KB article that gives two methods
to reset permissions which I've used--it was written in relation to service
pack install failures, but it is relevant otherwise as well..
Here's one like it, not the one I was thinking of, but it is XP, and would
not be sure that Vista permissions are the same--so I wouldn't try the steps
in this one:
http://support.microsoft.com/kb/949377
Hmm--you know--why waste our time digging for the right stuff: You are
unable to get security patches because WU is broken, right?
That's a free support call. In the U.S. or Canada 1-866-pcsafety
Elsewhere, the nearest number for paid Microsoft support, but ask for the
free help with security patch or virus infection issues.
The Microsoft folks on the phones will know how to do this right--it may
take a little persistence--I like to do this kind of thing by email--you can
see if you can spot the link to do that--it saves some time glued to the
phone--but in the end, they should be able to get this fixed.