Would I be right in assuming
I can only apply the 'Computer Configuration' Settings to OU's containing computer objects.
I can only apply the 'User Configuration' Settings to OU's containing users.
I am applying a GPO to an OU containing computers and trying to invoke a user logon script from the GPO Tree > User Configuration > Windows Settings > Script > Logon. This doesn't seem to work for me but I don't know whether I am looking at a fault or a feature.