>>>Try Setup.exe /qb+ /V"ALLUSERS=2"
>>
>>That gives me a dialog telling me what the valid command line parameters are.
>
>The only parameters InstallShield Express Setup.exe acepts are /L, /S and /V. For the silent installation try

setup.exe /s /V"ALLUSERS=2 /qn"

That gives me a dialog telling me "Error reading setup inialization file."

So does setup.exe /V"ALLUSERS=2" so I think there is something odd going on.