I cannot launch office xp setup.exe; encounter installer error

[Peddler]

Here is the message I get:

Windows Installer: This patch package could not be opened. Verify that the
patch package exists and that you can access it, or contact the application
vendor to verify that this is a valid windows installer patch package.
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I also get this message if I try to run "detect and repair" within any
Office XP application.