If your users are only members of the local Users group, they will not be able to use the Word 97 spell checker.
They do not have the required permission on the registry key involved.
Use Regedt32 to select:
HKEY_LOCAL_MACHINE\Software\Microsoft\Shared Tools\Proofing Tools\Spelling
On the Security menu, press Permissions. Press Advanced and highlight the local Users group.
Press the View/Edit button. Check the Allow boxes for Set Value and Create Subkeys.
Press OK and OK.