No connection could be made because the target machine actively refused it

I am trying to connect to a PostgreSQL server from another machine on my
small home network. When I click the Test button in the ODBC data mnager
for my system DSN I get the error "No connection could be made because
the target machine actively refused it." That may not be the exact
message but it is close.

I have no problem connecting using localhost on the machine where
PostgresSQL is running. However, if I connect using the machine's IP
address (10.0.0.9) either locally or from another PC I get the error
above. I have disabled the Windows firewall and my antivirus software
but the error persists.

Any suggestions? I am new to PostgreSQL so assume I have done something
really dumb.<g>

Bill