When performing an unattended install the following error message may be seen:

Windows could not parse or process unattend answer file [C:\Windows\Panther\unattend.xml] for pass [oobeSystem]. The settings specified in the answer file cannot be applied. The error was detected while processing settings for component [Microsoft-Windows-Shell-Setup].

Ensure that if plain text passwords are being used the PlainText setting is set to true.

    <settings pass="oobeSystem">
        <component name="Microsoft-Windows-Shell-Setup">
            <UserAccounts>
                <AdministratorPassword>
                    <Value>password</Value>
                    <PlainText>true</PlainText>
                </AdministratorPassword>
            </UserAccounts>
            <AutoLogon>
                <Enabled>true</Enabled>
                <LogonCount>1</LogonCount>
                <Username>Administrator</Username>
                <Password>
                    <Value>password</Value>
                    <PlainText>true</PlainText>
                </Password>
            </AutoLogon>
        </component>
    </settings>

Error message when you perform an unattended installation of Windows Server 2008: "Windows could not parse or process unattend answer file [drive:\Windows\Panther\unattend.xml] for pass [oobeSystem]"
http://support.microsoft.com/kb/947303