another interesting blog post. I just need to quote it.
The dramatic 'System Disabled' message is just scare tactics: when you remove all power from the laptop and reboot it, there are not new penalties such as additional passwords, locks and so on. From such a checksum (also called "hash"), valid passwords can be found by means of brute-forcing. Another method commonly used is that instead of a checksum, a number is displayed from which a randomly generated password can be calculated. Quite often, vendors also resort to storing the password in plain text, and instead of printing out just a checksum, an encrypted version of the password is shown.