Solution for ubuntu 9.10 to forget the root password (physical access is required)

This method is applicable to people who have physical access to machines.

1. Press Shift to go To the Grub menu.
2. Press e to modify the first "Ubuntu, 2.6.xxx-generic"
3. Modify the last 2nd lines. Set "linux/boot/vmlinuz... ro quiet splash" to "linux/boot/vmlinuz... rw single init =/bin/bash"
4. Press Ctrl + x to start the system.
5. Enter passwd root to change the root password.
6. Restart. Everything is done ~

So, the power-on password is only used to prevent the gentleman from defending against the villain ....