Errors 80072EFD or 8024502D and Windows Update V5 on XP (SP2)

I have seen a lot of posts regarding the two subject errors in Windows Update
V5. I have had similar problems and found that Norton Internet Security was
blocking outbound connections from SVCHOST.EXE (Microsoft Generic Host
Process for WIN32 Services as listed in NIS 2003). It took me a long time
to figure this out, since I had no idea that NIS might be doing the dirty
work, and Microsoft has been clueless.

If you are having either of these error codes it might help to make sure
your firewall is not blocking SVCHOST.EXE, since Windows Update V5 depends on
it.

I've seen a lot of posts, and can't reply to each individually, so I hope
that interested parties will discover this sooner rather than later.
--
RoyH