cannot connect from Windows 2000

We run Postgres on a solaris server.
I connect to the postgres database from win98 and winxp boxes using
postgres odbc driver ver. 7.02.00.05
works every time and i appreciate that.

but so far I am unable to connect from a windows 2000 server box on the
same network.
when i try to use control panel and set up a file dsn with the same
driver and same parameters, I get the error messsage "a connection could
not be made using the file datasource parameters entered"

I turned logging on, but nothing is written to c: so perhaps the
connection must be successful before anything is written to the log.

when I create a user dsn and then use a MS tool called ODBCTest and try
to connect I get SQL_ERROR=-1.
ODBCtest says I can get a detailed explanation of the error by clicking
an error button, but the button is disabled.

I have searched the postgres docs (admittedly not exhaustively) and
have come up with nothing.

I am a programmer not a network engineer and don't even know where I
should look next to search for the answer.

Any ideas?

Thanks in advance for any help you can extend.

Fred Parkinson