Unable to access server

I have a MAN that consists of 5 sites, 3 NT servers and 10 Windows 98 workstations at each site. I have 3 workstations at 2 sites that are not able to access 1 of 3 servers at 2 locations. The servers show in network neighborhood, but when I try to access them I receive an error “no access to \\server\. We are using TCP/IP as the protocol. I have completely deleted the NIC from the system and reinstalled the drivers and protocol. We are using DHCP. My game plan now is to replace the NIC.And if that doesn’t work reload the OS on the workstation. I’ve invested 3 hours playing with one of the computers already. ny suggestions before I get started.