Event ID 5504 and 5000

I am getting a repeated error 5504 on my NT 4.0 Server. With this error are several different IP addresses throughout the event log. The server is a DNS as well as a WINS server. At this time serveral clients are not able to find a domain server to connect to (the server these services are running on). My question is this… what causes this error, and what can I do to fix this error. The error 5000 relates to the excessive amounts of time that this error is being reported. Thank you to anyone who can assist me with this.