You need Windows Update Agent 3.0 after the XP SP3 update
One more interesting read on Microsoft XP SP3 installation by Mark Dormer, MVP.
Windows XP SP3 breaks Windows Update
If you install XP SP3 on a clean SP2 box, Windows Update will no longer work. Unless you have the newer Windows Update Agent 3.0, you're stuck in a hole. There is no way to get it via AU or WU or MU; only a manual installation can resolve the issue.- Download the new agent (but do not run it yet) to your desktop (so you can find it below). X86 Version download.
- Start, Run, CMD
In the black box:
net stop wuauserv
“%userprofile%\Desktop\WindowsUpdateAgent30-x86.exe” /wuforce (don’t forget the quotation marks)
net start wuauserv exit
The original post.
not sure what I was doing wrong but kept getting an invalid file message. I was able to do the stop. Since it wouldnt take the file, I just restarted and am back to square one
Please follow next link for complementary info.http://technet.microsoft.com/en-us/library/bb932139.aspx