problem with psql?

We just ran an OS update on an Xserve which runs our PostgreSQL
server, and now it seems that pg_ctl status doesn't report the
correct status.

~ postgres$ pg_ctl status
pg_ctl: neither postmaster nor postgres running

~ postgres$ ps auxw | grep postgres
postgres 491 0.0 -0.1 33156 1160 ?? S 1:09PM
0:00.16 /usr/local/pgsql/bin/postmaster -D /Volumes/DBRAID/pgsql/data
postgres 629 0.0 -0.0 31844 216 ?? S 1:09PM 0:00.27
postgres: logger process
postgres 631 0.0 -0.0 33140 744 ?? S 1:09PM 0:00.06
postgres: writer process
postgres 632 0.0 -0.0 31860 276 ?? S 1:09PM 0:00.02
postgres: archiver process
postgres 633 0.0 -0.0 32864 164 ?? S 1:09PM 0:00.02
postgres: stats buffer process
postgres 634 0.0 -0.0 31888 284 ?? S 1:09PM 0:00.03
postgres: stats collector process

We are able to connect to the instance (using psql), but cannot shut
down or restart the instance using pg_ctl (it just reports that the
server is not running). We are running PostgreSQL version 8.0.0 and
Mac OS X 10.3.9. Can anyone tell us what's going on?

Thanks!
Tim