Outlook can’t access Exchange

This may not belong in the NT forum, but I’m not sure it’s strictly OFFICE either:
I have an installation of Small Business Server 4.5. The workstations have Outlook 2000 with Global address book and email through Exchange running on the server. All stations but one work fine (Win 98). Somehow, no matter what I do (re-install, etc), I can’t get Outlook to recognize Exchange resources. There’s no problem with connectivity for files/printers. When installing, Outlook hides the options, etc. which relate to non-local functions of Outlook. I’ve deleted & re-installed more than once. Is there a special protocol that Exchange needs?