Group policies not applied to all 98 workstations

I support a network in a school that has a single NT4.0 DC
and 65 workstations running a mix of 2000 pro and 98se. I
have created a config.pol file using a 98se workstation
which has been placed in the netlogon share of the DC. The
workstations I am concerned with are Dell GX110 (older)
and GX150 (newer). The group policies are properly applied
when a student logs on at a GX150, but are not applied
when logging on to a GX110. I suspect there is some
difference in the settings of the workstations prior to
enabling group policies through the add/remove programs on
the control panel, but I cannot identify what they might
be. I have tried removing the default user and default
system from config.pol and that does not change anything.

Anyone have an idea?

Thanks,
Marcus