If the problem persists after checking the network settings, do a quick test to see if the cable is at fault. Borrow a cable that you know is good from another node. Plug it in and see if the node works. If it doesn't, you know you need to permanently replace the cable. Single user has no zones, no IP connectivity.
Ethernet card is bad.
The server or host machine for that service is down. Tell your users to relax and work on something else in the meantime. Multiple users have no zones, no IP connectivity, but local resources such as printers and file servers are available. Call the NOC at 5-9900 with the IP address of your gateway. Multiple users have no zones, no IP connectivity, but local resources such as printers and file servers are not available.