WSUS: Code 643 Windows Update encounter an unknown error.

Have you gone over?


http://support.microsoft.com/kb/976982

This update is not the .NET framework. It is a ForeFront update.

Try method 1 regardless

Stopping forefront services may also do it for you


http://nukeitmike.com/blog/2009/03/25/error-installing-update-for-microsoft-forefront/

This is a HP laptop. I don't see any ForeFront on the user's laptop. However, I will check again on the laptop tomorrow morning.

The ForeFront is not on the laptop. I tried to hide that update or deleted uninstall updates from folder SoftwareDistribution. However, it did not work.

Did you run the fix-it ?

http:#a37562093


Or try the System Update Readiness Tool

http://windows.microsoft.com/en-US/windows7/What-is-the-System-Update-Readiness-Tool

I found this error "There is another Microsoft antimalware product installed that you must uninstall before you can install Forefront Client Security."
I am going to find out which another Microsoft antimalware product is installed on the laptop.

Do you know how to delete that uninstall update permanently? I went to Folder SoftwareDistribution and deleted everything but that update is still there.
Thanks

I declined that update in WSUS and remove all updates from folder SoftwareDistribution and run the .bat file you gave me. I hope it works.
Thanks,