a problem in authority

Hi, all
I have installed the Postgresql 7.3 . But I think something is wrong with authority.
I have made the following operations:
1. I enter the psql and run 'alter user postgres with password 'postgres''
2. I change the pg_hba.conf and set the auth_type from 'trust' to 'password'
3. Then I can not connect to server.
I have test connect from local or connect from host, but it just return 'authority fail for user postgres'.
I can connect to postgresql 7.23 successfully after above steps;
Great thanks for any message.
Josh