Small Business B/O Server 2000-Internet

Operating System: Small Business Back Office Server 2000.
Problem: set up a dial in account for our ISP. Dial the ISP connection and you get connected. Go to internet explorer and you get the message “Page cannot be displayed” for any web address but you can ping any of these addresses. Try to download mail and you get the message – “Failure to upload/download”. Current theory is some kind of firewall but don’t know what to do.