To install this security update, you must have Micro$oft Windows Installer 3.1
installed on your computer.
To obtain the latest version of Windows Installer, go to the Windows Download Center.
Note that that update KB927891
was offered in the Automatic Windows Updates on May 22,07.
If that update (KB927891) is already listed in Add/Remove Programs, (be sure that the "Show Updates" box is checked), then it's already installed.