It MIGHT be a Postgres permissions/user issue.  Make sure that you have a valid Postgres user (different than a Linux user) that can create databases.  You can test by logging in to Postgres command line interface as that user and trying to create a dummy database.  If you can create a DB with that user then make sure that this user's name and password are the ones in the openerp-server.conf file.

You can find out how to create users and DBs by checking "createuser" and "createdb" in Postgres' help on their website: http://www.postgresql.org/docs/9.1/static/reference-client.html