Flash MSI object install to workstation with normal user account

I've created an MSI object for the Flash 9 plugin, which installs okay
on the workstation when I login with an admin user. It will not
install when logged in with a normal user account. I have set it up as
an unsecure user and given the workstation R and F rights to the msi
object, but I'm still getting a 1603 error code.

Can anyone help?