Yes, I created a separate domain, and registered the node "sql_ntserver50"
in that domain on my one and only server. When I look at it, it all seems
right to me. But when I try to backup a SQL database with that node name, it
fails, with NO meaningful error messages except those pertaining to MSSQL's
inability to write to the backup pipe.  If I simply change the node name to
"ntserver50", which is registered with the server for file backups, it backs
up just fine.

Are other folks not having this problem?