pgAdmin error

I am trying to use pgAdmin 1.8.4 to edit the pg_hba.conf file on a
PostgreSQL 8.3 database running on Ubuntu 8.10. I get the following
error message:

An error has occurred:

ERROR: absolute path not allowed
CONTEXT: SQL function "pg_file_length" statement 1

then...

Backend Access Configuration Editor -
/etc/postresql/8.3/main/pg_hba.conf on Kepler...

with a blank screen.

My configuration seems ok. Any help?

from the pgadmin.log

2008-11-22 01:20:21 INFO : Server name: kepler.fdu.edu (resolved to:
132.238.16.3)
2008-11-22 01:20:21 INFO : Opening connection with connection string:
host='kepler.fdu.edu' hostaddr=132.238.16.3 dbname='postgres'
user='david' password='XXXXXX' port=5432 sslmode=require
2008-11-22 01:20:24 QUERY : Set query (kepler.fdu.edu:5432): SET
DateStyle=ISO;SELECT oid, pg_encoding_to_char(encoding) AS encoding,
datlastsysoid
FROM pg_database WHERE oid = 11511
2008-11-22 01:20:24 INFO : Setting client_encoding to 'UNICODE'
2008-11-22 01:20:24 QUERY : Set query (kepler.fdu.edu:5432): SELECT
proname, pronargs, proargtypes[0] AS arg0, proargtypes[1] AS arg1,
proargtypes[2] AS arg2
FROM pg_proc
JOIN pg_namespace n ON n.oid=pronamespace
WHERE proname IN ('pg_tablespace_size', 'pg_file_read',
'pg_logfile_rotate', 'pg_postmaster_starttime', 'pg_terminate_backend',
'pg_reload_conf', 'pgstattuple', 'pgstatindex')
AND nspname IN ('pg_catalog', 'public')
2008-11-22 01:20:24 QUERY : Scalar query (kepler.fdu.edu:5432): SHOW
hba_file
2008-11-22 01:20:24 QUERY : Query result:
/etc/postgresql/8.3/main/pg_hba.conf
2008-11-22 01:20:24 QUERY : Scalar query (kepler.fdu.edu:5432): SELECT
pg_file_read('/etc/postgresql/8.3/main/pg_hba.conf', 0,
pg_file_length('/etc/postgresql/8.3/main/pg_hba.conf'))
2008-11-22 01:20:24 ERROR : ERROR: absolute path not allowed
CONTEXT: SQL function "pg_file_length" statement 1