Dan, had the same problem until this afternoon. There was a post on 7/23 by
Andrew McLaren that solved the whole thing for me in about half an hour
(would have been quicker but my wife had other things for me to do at the
same time). Here is the solution from that post:
"Thanks and kudos to Chris Rowat, who first provided this solution over in
the MSDN forums :-
1) Download and run the Windows Installer Cleanup Utility. Use it to remove
the .NET Framework 1.1 from the machine.
Windows Installer Cleanup Utility
http://support.microsoft.com/kb/290301
2) Download .NET Framework 1.1 from the Microsoft website (don't download
via Windows Update), and save it to your hard disk (file name dotnetfx.exe).
..NET Framework 1.1
http://www.microsoft.com/downloads/...E3-F589-4842-8157-034D1E7CF3A3&displaylang=en
3) Download .NET Framework 1.1 Service Pack 1, and save it to your hard disk
(file name NDP1.1sp1-KB867460-X86.exe)
..NET Framework 1.1 Service Pack 1
http://www.microsoft.com/downloads/...4F-088E-40B2-BBDB-A83353618B38&displaylang=en
4) Run the downloaded dotnetfx.exe to install .NET Framework 1.1.
5) Reboot your machine.
6) Run NDP1.1sp1-KB867460-X86.exe to install .NET Framework 1.1 SP1.
7) Reboot your computer again.
8) Now run Windows Update again, to install post SP1 hotfixes.
Not all the reboots maybe necessary, but ... better safe than sorry.
Caveat: I have not used this myself (I never got the 643 error). But many
folks in MSDN forums have confirmed this procedure has fixed the "643" error
for them. There may be other solutions, too.
Hope this helps,
--
Andrew McLaren
amclar (at) optusnet dot com dot au"
Hope this works for you, assuming you haven't found a solution as of yet.
Regards