Can't connect remotely

We've recently installed Postgresql 8.3 on a Windows Server 2003, Standard Edition, Service Pack 2 machine. I am able to connect locally via pgAdmin but not remotely.

The error message we are receiving in the Application event log is...

XX000: could not bind IPv4 socket: No error

The above occurs twice and then we get

WARNING 01000: could not create list socket for "loaner-mikec"

Our postgresql.conf contains...

#------------------------------------------------------------------------------
# CONNECTIONS AND AUTHENTICATION
#------------------------------------------------------------------------------
# - Connection Settings -
listen_addresses = 'localhost,marlon,loaner-mikec'
# what IP address(es) to listen on;
# comma-separated list of addresses;
# defaults to 'localhost', '*' = all
# (change requires restart)
port = 5432 # (change requires restart)
max_connections = 100 # (change requires restart)

host all all marlon/32 trust
host all all loaner-mikec/32 trust
host all all marlon trust

marlon, and loaner-mikec are two machine names from which we're trying to connect. We previously tried using ip address instead of machine names, but got the same negative symptoms.

Any help greatly appreciated.