Error on postgresql driver (or pg_hba)

I'm getting the following error from my application log file. I'm using
Postgres 7.1.2 running on HP-UX 11.0. These errors are results from our
Java servlet programs using the postgresql driver:

"Something unusual has occured to cause the driver to fail.
Please report this exception: java.sql.SQLException: Missing or erroneous
pg_hba.conf file, see postmaster log for details"

When it happens the connection is broken as can be seen from the following
messages in my postmaster logs:

"pq_recvbuf: unexpected EOF on client connection"
"Missing or erroneous pg_hba.conf file, see postmaster log for details
find_hba_entry: Unable to open authentication config file
"/opt/postgresql-7.1.2
/data/pg_hba.conf": File table overflow"

An extra note, we use JRun 3.0 which I'm quite sure has a built in
postgresql driver so this could be the problem but I have not looked into
this possibility in depth.

Everything else seems to be working fine i.e. psql, dumps etc., and also the
db continues functioning as normal after the error occurs. Of course our
application would fail at the time it happens but goes on as normal upon
subsequent retries but would occur again from time to time.

I'm hoping to get some tips on how to find the root of the problem, or point
me to somewhere with more info regarding the above error.

Thanks in advance...will post this to hackers within 24 hrs :)

Ron Looi
Consultant