Strange permission problem regarding pg_settings

Hi

I installed a postgres-application (which was developed on debian
woody) on red hat 9 today, using the postgres 7.3 rpms from redhad.
One of my the triggers uses the pg_settings table (more precisely, it
updates that table to change the search_path temporarily). With the
postgres 7.3 (and 7.4 too) installed on my debian development system,
this worked fine. On redhat 9, however, I get an "pg_settings:
permission denied" error when my trigger is executed.

The same thing happens when I try altering the pg_settings table from
the commandline. (But of course works, when connected as superuser). I
double-checked the permissions set on both the pg_settings view, and
the set_config(text, text, bool)-function called from the update-rule
for pg_settings, and both seem to be correct (and the same as on the
debian machine).

As I needed to get the thing running, I now solved the problem by
making the user that my app connects as a superuser, but I'd like to
get rid of this again...

Are there any more permission I could check, or perhaps some
config-option in postgres.conf that I could try?

greetings, Florian Pflug

PS: I also tried moving the postgres-data-dir away, and creating a
fresh one with initdb - but with no success - still "pg_settings:
permission denied"