This is almost as if I was reading my self :P
I too fix comps for living, and loaded a brand new PC with Windows XP SP2
OEM, then installed all of the drivers and then proceeded to Microsoft
Update. It loaded SP3, rebooted and then wouldn't update anymore. I spent
like 2 hours looking for the right fix, i found this fix quite soon, but
didn't bother trying it, looked too simple to work

So, SP3 is definitely
the one responsible for this error here, I didn't install ANYTHING else, just
WinXP SP2, drivers, update (WGA and others, that it installs first), then SP3
and right after SP3 it didn't update anymore. Hope M$ fixes this soon, until
then, batch file with these commands is working overtime on my trusty old USB
key when I update all the PCs to SP3..
"Corey" wrote:
> I am a registered partner with Microsoft and fix PCs for a living. I also
> loaded a PC with XP (original), installed SP2 and then SP3 (the full network
> install version I keep handy on my flash drive). Windows downloaded a few
> updates of it's own automatically and I allowed them to be installed. Then I
> installed some programs (Legacy Family Tree, AVG 8 Free, Quicktime, Adobe 8
> Reader, and Office 97) and tried to install some driver updates from the
> Windows Update Site. I also could not get any updates to load - NOT EVEN THE
> GENUINE ADVANTAGE VALIDATION TOOL.
>
> I tried the suggested fix and it worked. This is a common problem when
> spyware has disabled these DLL files, but this time either one of those
> programs or SP3 has done it. My guess is that it was SP3. I hope this helps
> MS to find out what has happened and how to fix it with SP3.1.
>
> Corey