The new Control Panel 3.0 is not backward compatible with older System files.
Previously, the setting of the mouse scaling option (set by the Control Panel
and used by the System file) was stored in a single bit in the battery
backed-up parameter RAM. Because the new system offers a larger choice of
scaling options, the format of the saved setting had to change. This is why
older version of the System file can't properly read the settings saved by
the new Control Panel.