I am using Windows 7 Professional, 64-bit OS. I have recently encountered problem on windows updates, with error code 80004002. I have tried to reinstall the Windows Update client (following the guidance under the Windows Help & Support).
However error message "Windows Update Agent Installer Fatal Error : Windows Update Agent Installer encountered unrecoverable error." appeared during the installation.
Also, try the steps in the following Microsoft Support article.
Error message when you try to install updates by using the Windows Update or Microsoft Update Web site: "0x80004002": http://support.microsoft.com/kb/956708/en-us