"Password" issues -- bug??

Hi there,

First off, let me tell you that I've tried successfully the "trust" option in pg_hba.conf
I've also searched as much litterature as possible on my issue but it always comes down to the pg_hba.conf trick.

It just happens that I cannot connect to the server without the "trust" option set. In other words, when I restore md5, I cannot manage to authenticate anymore.

Of course, I've done an ALTER USER, triple checked that the password is the same, etc. I cannot make it seem to work.

I've tried with both psql and pgAdmin3.

My config:
PostgreSQL 9.0.2
Mac OS 10.7.5

(can locale have something to do with it? Is so, you want to know that I've tried with a full C locale for the environment that starts the server + psql, as well as with "fr_FR.UTF-8")

Any clue on what this could be?

thanks
Arnaud