Problem with Office & Windows XP

On our Novell network, I have my Compaq Deskpro EP Pentium 450 with 256 ram with the latest Novell Client for XP 4.83 When accessing our Exchange 2000 server, I get a message “Microsoft Exchange Server is unavailable” with the Retry, Work Offline, Cancel. When I hit Retry it goes in on the second try. I’ve changed the timeout settings from 30 to 45, 60, 90 120 seconds, I’ve even typed in the ip address and it won’t hold the ip address to the server. I’ve even tried the hosts file and that won’t work. Any suggestions?