A tool from Microsoft to clean up patch registration when you have issues with installing Windows Installer based updates.

  • Supported Operating Systems: Windows 2000; Windows 7; Windows Server 2003; Windows Server 2008; Windows Server 2008 R2; Windows Vista; Windows XP

Download details: Patch Registration Cleanup Tool

NOTE: Unfortunately, as of Oct. 13, 2009 the KB article mentioned is not yet posted.