I got this fix
from Microsoft support. It works, I did it. I did tell them
that the problem seems to be Microsofts because there are too many of us
experiencing the same problem.
To troubleshoot this issue, I suggest we first perform these steps:
Step 1: Download Microsoft Windows Installer CleanUp utility
2. Save the file to your computer.
3. Right click "msicuu2.exe", click "Run as administrator" and follow the
wizard to install this tool on your computer.
Step 2: Remove .NET Framework
1. Click Start ->All Programs->Windows Installer Clean Up, click Allow.
2. See if you can find .Net Framework software. If so, remove them.
After that, please restart the computer and perform the following
suggestions to reinstall .NET framework 1.1 and the updates for it.
Step 3: Install .NET Framework 1.1 Redistributable Package and related updates
1. Please download the Microsoft .NET Framework Version 1.1 Redistributable
Package from the following link and save it to the C drive (C:\)
1) Microsoft .NET Framework Version 1.1 Redistributable Package
2) Microsoft .NET Framework 1.1 Service Pack 1
3) Security Update for Microsoft .NET Framework, Version 1.1 Service Pack 1
4) .NET Framework 1.1 Service Pack 1 SYSTEM.WEB.DLL and MSCOREE.DLL Security
Update for Windows Vista (KB929729)
> This error code relates to a "security update for Microsoft.NET framework
> version 1.1 Service Pack 1. My Windows Vista has tried many times to
> download this update and each time it has failed and reports error code 643.
> What is the solution to this problem?