Computers stopped accessing the Internet

I am running NT 4.0 on our server and our workstations are using Win98SE. We have about 20 computers with access to the internet, but within the last week about 4 computers stopped accessing the internet altogether. The workstations that are not getting access are getting a DNSError but I can find no reason why they would stop working. Our network uses DHCP, so I have no settings for DNS in my TCP/IP properties in network neighborhood. If anyone has an idea what could be causing this, please let me know.