My group was facing an issue where we did not remember the password for admin@System-Domain, so we executed the help posted by memaadJun 13, 2013 2:43 PM.
It worked and helped us out tremendously.
Our situation was slightly different in that we did not have the web client installed.
One thing to note is that if you previously attempt username password combinations that fail beyond 3 attempts, even the new password set via memaad's method fails. The Single Sign On (SSO) will lock you out for 15 minutes, so make sure to wait at least 15 minutes.