Tim,
This most likely means that your staff doesn't have the latest version
of Silverlight installed. Can you check the Silverlight version of
machines that failed? Right click on a Silverlight app and it will
tell you about the version. If Silverlight is freshly installed on a
Mac machine, it will also fail, but a reboot will fix it. I cannot
downgrade the version required by Tagxedo as it does depend on the
latest version (as of a few months ago).
-- Hardy