BUG #5931: password when setup

The following bug has been logged online:

Bug reference:      5931
Logged by:          mac
Email address:      wesleygu@hotmail.com
PostgreSQL version: 9.0
Operating system:   WIN7
Description:        password when setup
Details:

when i install the software, after i choose the directory of software, the
SETUP need me input the password. this afternoon in another computer, i
input "postgres" to continue, but at my home, i try "postgres" or
"postgrespass", it all says "the password specified was incorrect. Please
enter the correct password for the postgres windows user account", so i cant
continue.
please help me!