To break the GRUB start-up password, follow the steps given below:
1. Boot the system with the first Linux CD. At the boot prompt, type linux rescue to switch to rescue mode. In rescue mode you will be asked if similar steps should be followed, which need to be followed in the installation. Once you get the # prompt, type the following command:
# chmod /mnt/sysImage
2. Edit the grub.conf file and remove the passwd line from the file. Save the file and exit.
3. Once your machine reboots, you will be able to start your Linux OS in the usual manner.