I assume you have made your installations based on the standard installables. Last year I had the same problem.

AFAIK the user and pasword for the windows setup and the ubuntu setup are different!

It is best to check the configuration file for the correct user and pasword to use.

Added later: For the versions I used it was:

• Ubuntu: user= openerp pasword=postgres
• Windows: user= openpg pasword=openpgpwd

For connection with pgAdmin:

• Host: localhost
• Port: 5432 SSL blank
• Maintenance DB: postgres

If you try to make a remote connection you get standard a connection error. For security reasons this is not allowed. If you want to change this you need to change the configuration paramaters.

try accessing the database with pgadmin from a different machine. Looks like you have a problem with the username and password. You can find further information here:

http://www.postgresql.org/docs/9.2/static/user-manag.html

Joshua, in order to open PostgreSQL database from other machine you need to setup 3 things:

• The database server need to listen to other addresses.  This configuration is set in postgresql.conf under the listen_addresses key.  If you want the database server to be accessible from anywhere you can put '*' in place of 'localhost'
• You need to check that your user has access to the database server from a specific network (IP address) and what authentication method is configured for that connection.  The configuration is stored in pg_hba.conf.  Each uncommented lines (those without # in front) represent allowed access method.  The lines on the top take precedent over the lines below it.  Each line must be in the following format.  The file itself has explanation on how to configure an access.  The configuration is usually set at the strictest level by default.  Most of the time, it is safe and convenient to configure access using md5 method.
• Once you have both configured correctly, you have to ensure that you follow the allowed access method.  md5 means that you need to supply the correct password, peer means that the password used will be the same as the OS password (which may not what you want).

Go to openerp-server.conf file( use this command ,sudo nano /etc/openerp-server.conf), open  and check the  username and passord .Login with this username and password in postggres