Problem send/receive mail in outlook

Our company uses exchange 5.5 in a windows 2000 domain.A windows 98 pc on our network is giving problems with Outlook 2000 SR1. When an email is sent that mail sits in the outbox instead of automatically forwarding. The email will only forward to the appropriate address when the user clicks on any other folder in the folder list. Similarly, when an email is sent to the inbox, it only registers in the inbox when the user clicks on any folder in the folder list.