su postgres: Sorry?
i have a really urgent problem with my postgreSQL setup on my new Mac OSX Lion machine.

I can't seem to connect to the service

    $ createuser -a -d _postgres
    Password: 
    createuser: could not connect to database postgres: FATAL:  password authentication failed for user 

I have no chance to find the correct password. Any idea what could that be. I have the default setup with a localhost server. The same happens when I try to connect via pgAdmin. 

    $ su postgres
    Password:
    su: Sorry

I have no chance to find out what's wrong?
su postgres: Sorry?
===

i have a really urgent problem with my postgreSQL setup on my new Mac OSX Lion machine.

I can't seem to connect to the service

    $ createuser -a -d _postgres
    Password: 
    createuser: could not connect to database postgres: FATAL:  password authentication failed for user 

I have no chance to find the correct password. Any idea what could that be. I have the default setup with a localhost server. The same happens when I try to connect via pgAdmin. 

    $ su postgres
    Password:
    su: Sorry

I have no chance to find out what's wrong?