You are getting the error, Invalid user or password, but you installed the system with the Don't Prompt option, so the password should be supplied automatically.
The correct password may not have been specified during installation, or it may not be passed when the domain is started.
Check the password in the .asadminprefs file. On UNIX/Linux systems, it is in the home directory for the user under which the server was installed. On Windows, it is in C:\\Documents and Settings\\username. The contents look something like this:
AS_ADMIN_USER=admin AS_ADMIN_PASSWORD=administrator