Server Closed Connection Unexpectedly

I'm hoping you can help me.

I am having trouble connecting to a remote Postgresql 7.4.2 database from
pgAdmin3 for Win32. I've tried using 2 different versions (1.02 and 1.20)
on 2 different Windows boxes in 2 different locations. I've tried
connecting as different users to different databases. Each time I
immediately get:

An error has occurred:
server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.

The local pgadmin.log in debug mode shows something like:
2005-01-05 14:44:10 INFO : Destroying a connect dialogue
2005-01-05 14:44:10 STATUS : Connecting to database...
2005-01-05 14:44:10 INFO : Creating pgConn object
2005-01-05 14:44:10 INFO : Server name: csl-db-01.thecsl.org (resolved to: 129.63.24.86)
2005-01-05 14:44:10 INFO : Opening connection with connection string:
hostaddr=129.63.24.86 dbname=foobar user=foobar password=mypassword port=80
2005-01-05 14:44:11 QUERY : Set query (csl-db-01.thecsl.org:80): SELECT
pg_encoding_to_char(encoding) AS encoding, datlastsysoid
FROM pg_database WHERE datname='foobar'
2005-01-05 14:44:11 ERROR : server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.

2005-01-05 14:44:12 STATUS : Connecting to database... (1.50 secs)
2005-01-05 14:44:12 ERROR : Error connecting to the server: server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.

2005-01-05 14:44:13 INFO : Destroying pgConn object
2005-01-05 14:44:13 INFO : Destroying a pgServer object
2005-01-05 14:44:13 INFO : Creating a pgServer object
2005-01-05 14:44:13 INFO : Attempting to create a connection object...
2005-01-05 14:44:13 INFO : Creating a connect dialogue
2005-01-05 14:44:14 INFO : Destroying a connect dialogue
2005-01-05 14:44:14 INFO : pgServer object didn't initialise because the user aborted.
2005-01-05 14:44:14 INFO : Destroying a pgServer object

A look in the server's logs always shows something like this:
Jan 5 14:44:14 csl-db-01 postgres[4606]: [12-1] LOG: connection received: host=70.19.142.198 port=50833
Jan 5 14:44:14 csl-db-01 postgres[4606]: [13-1] LOG: connection authorized: user=foobar database=foobar
Jan 5 14:44:14 csl-db-01 postgres[4606]: [14-1] LOG: could not receive data from client: Connection reset by peer
Jan 5 14:44:14 csl-db-01 postgres[4606]: [15-1] LOG: unexpected EOF on client connection

I have no problem connecting to the database by other means (e.g.
hand-coded Java via jdbc, psql, as well as pgAdmin3 (1.02 and 1.20) from
a Debian box).

Any help would be greatly appreciated.

Thanks!
-David