Trouble connecting between postgresql machines

Hello: I recently installed postgresql 6.3.1-2a on my mklinux box.
I have an existing postgresql version 6.2.1 on my Sun Solaris 2.5.1
machine. I have been unable to contact the older database from mklinux
via psql. I continue to get the error:

Failed to authenticate client as postgres user 'huntd' using <unknown
authentication type>:be_recvauth: unrecognized message type: 65536

I have verified that both databases are open to connections from anyone,
anywhere. I know that the user 'huntd' is in my pg_users table on the
older machine. The user id of 'huntd' is the same on the old and new
machines.

I'm not sure what's going on. Am I missing some authentication detail,
or is there a problem communicating between postgresql versions?

Any help would be much appreciated,

Doug Hunt

Software Engineer
dhunt(at)ucar(dot)edu

--
dhunt(at)ucar(dot)edu
Software Engineer III
UCAR - GPS/MET
Tel. (303) 497-2611