Giedrius, you may be onto something. Because this is a production server, and during Disaster Recovery testing we are restoring the full domino server from tape, it could be that the OS name has the "wrong" Primary DNS suffix.
On the production server, it's in our WIndows domain, so it's DominoServer.AD_Domain.com
However, the original author of the operating system component of the script we use for Disaster Recovery has the correct computer name for the server, but has the Primary DNS suffix set to our company's Internet domain.
I'm going to make a note to change that setting during next years' test, and see if that error still occcur.
There is an entry in the hosts file on the recovered server that points to it's fully qualified internet host name (which is different than the server name) and it's correct IP.
And the DNSServer= line in the notes.ini is correct as well.