Hello.
I have recently tried to install PunBB with table prefix on my PostgreSQL, after install I am getting "Unable to fetch user information.", and after refreshing to forum / I am getting "config.php is non existant of corrupt" error. Without table prefix specified it works. Problem is I need table prefix. 
Of course I checked if config.php is in the right place and has correct permissions.
List of databases
Name | Owner | Encoding
-----------+---------+----------
forum | forum | LATIN2
root=# \c forum
You are now connected to database "forum".
forum=# \d
List of relations
Schema | Name | Type | Owner
--------+-------------------------+----------+-------
public | pbb_bans | table | forum
public | pbb_bans_id_seq | sequence | forum
public | pbb_categories | table | forum
public | pbb_categories_id_seq | sequence | forum
public | pbb_censoring | table | forum
public | pbb_censoring_id_seq | sequence | forum
public | pbb_config | table | forum
public | pbb_forum_perms | table | forum
public | pbb_forums | table | forum
public | pbb_forums_id_seq | sequence | forum
public | pbb_groups | table | forum
public | pbb_groups_g_id_seq | sequence | forum
public | pbb_online | table | forum
public | pbb_posts | table | forum
public | pbb_posts_id_seq | sequence | forum
public | pbb_ranks | table | forum
public | pbb_ranks_id_seq | sequence | forum
public | pbb_reports | table | forum
public | pbb_reports_id_seq | sequence | forum
public | pbb_search_cache | table | forum
public | pbb_search_matches | table | forum
public | pbb_search_words | table | forum
public | pbb_search_words_id_seq | sequence | forum
public | pbb_subscriptions | table | forum
public | pbb_topics | table | forum
public | pbb_topics_id_seq | sequence | forum
public | pbb_users | table | forum
public | pbb_users_id_seq | sequence | forum
(28 rows)
platinum:/root# ls -lh /srv/www/htdocs/forum/config.php
-rw-r----- 1 httpd httpd 303 2006-12-12 16:51 /srv/www/htdocs/forum/config.phpRegards.