pg_connect socket creation error (0x0000273F)

Hello.

I've been fighting with this all day, trying to fix it but I
couldn't. So here I am. I have Cygwin installed in a Win XP machine.
PostgreSQL is running there. Apache and PHP are installed in Windows
in the same computer. PostgreSQL is properly configured (even psql
and pgAdmin III work).

Since I've heard that sockets are more efficient that connecting to
localhost, I decided to uncomment the lines:
tcpip_socket = true
port = 5432
in the postgresql.conf file.

But when I removed the host parameter from the connection string:
pg_connect('dbname=mydb user=myuser password=mypass')

I got this message:
Warning: pg_connect(): Unable to connect to PostgreSQL server: could
not create socket: An address incompatible with the requested
protocol was used. (0x0000273F) . in c:\htdocs\testsockets.php on
line 2

What does this line "An address incompatible with the requested
protocol was used." means?!?

I've looked similar errors in this list and google but I couldn't
find an answer. Some people wrote that could be a problem in the
pg_hba.file. I tried there too, but didn't work:
host all all 127.0.0.1 255.255.255.255 trust

I would appreciate any help. Thanks.
Regards, Douglas.

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