Novice having trouble getting started

All, we've installed postgres 8.3 on a server running Windows Server 2003. When working directly on that server, I was able to connect with the database through PGAdminIII. So far so good ...

Next we tried to access the database remotely via LAN using the local machine's Windows XP ODBC configuration service, which asks for the database name, server name, user name, port, and password. The server kept refusing access, saying our request had been "actively refused" . The error message echoed our remote machine's IP address, followed by a colon and the default postgres database port number (5432). What are we doing wrong?

The other problem now is that the postgres service keeps shutting down by itself in Windows Server 2003. For the first several days after installing postgres on the server, the postgres service ran just fine. But now it won't run properly. We had this experience once before with another server but thought the problem was on that server. But the current server is clean, no other database server programs installed.

Any help will be very much appreciated!!!

I can think of two things:
1) Is there a firewall on the server?
2) Your Postgres service is only accepting connections from localhost (which is the default setting)

Check your postgresql.conf

There is a setting called "listen_addresses" if that does is commented out (# at the start of the line) the Postgres service will only accept connections from localhost.
You have to uncomment the line and then put * into the value, e.g.
For more details see the manual:
http://www.postgresql.org/docs/8.3/static/runtime-config-connection.html

Thanks very much for the advice. Now, trying to start postgres locally on the server, I get a rejection of the pg_hba.conf entry. The configuration line reads:

host all all (IP address) trust

According to the log file, the rejection is based on the keyword "trust". I've tried using the word with and without quotation marks, and I've tried the md5 option. The same error message each time, the pg_hba.conf file is missing or erroneous.

Any ideas here?

You did read the manual, did you?

Quote from the manual at: http://www.postgresql.org/docs/8.3/static/auth-methods.html#AUTH-TRUST

"trust authentication is appropriate and very convenient for local connections on a single-user workstation"

I guess you want some kind of password protection. So make sure your user has a password assigned and change the method to md5 (no quotes)