I went to www.eventid.net and found this:
The NETLOGON service is responsible for adding most of the domain configuration SRV resource records (RRs) to the DNS service used by the domain. Each time the netlogon service is started, it attempts toregister the domain configuration SRV RRs in the DNS server. (In other words, "net stop netlogon" and "net start netlogon" can be a useful sequence to debug this problem.)
If Event ID 5782 is reported, it may also be that all the appropriate domain configuration SRV resource records have disappeared from the DNS server (particularly if the DNS server is set to savage old records). If these records (the _msdcs, _sites, _tcp, _udp records) have disappeared, then the "dcdiag" command and the "netdiag" command will both report errors on the DC. "netdiag /fix" (run on the DC), will add these records back to the DNS server. In addition, the "nltest" command may be helpful in diagnosing problems with the netlogon service and the DNS configuration.
For Windows 2000 domain controllers that did not experience this problem prior to SP1, then the problem is most likely the result of a change with SP1. In the TCP/IP properties for a connection, under the advanced settings, DNS tab, is a checkbox for "Register this connection's addresses in DNS." With SP1, if this box is not checked, then the Event ID 5782 problem will surface. With SP1, if this box is not checked, then netlogon registrations are disabled as well. Prior to SP1, this was not the case.
The full article is here:
http://www.tuketu.com/technology/win2k-event%20id%205782.htm
(delete any spaces in the URL)
Hope it helps!