Using a Windows computer, editing the file: C:\WINDOWS\system32\drivers\etc\hosts the localhost entry was remapped to the machine name by adding the following line: 127.0.0.1 <Computer-Name>
After this change, Postgres would not allow access using the address localhost. Only using the machine name to access the database was possible. Is this by design? In other words psql -h localhost fails, but: psql -h <Computer-Name> succeeds.