Windows 2000 DNS Server and Members

I am a student and in class we created DNS servers and member(s). One of the members could not ping or connect to the DNS server. I checked the cabling (it was not that), I pinged the local host and the NIC seemed to be fine. I checked my settingsand they were all correct. Why would that one machine not recognize the domain? We use removable hard drives for the different classes, when I inserted another drive in the machine it was able to ping the domain server. Why? What was going on?