The steps to change the Root password in Cent OS 5.4 is different from the previous versions.
Here are the steps:
At boot time, interrupt grub by quickly pressing any key. The <space bar> is recommended as being the easiest.
You should now see the grub menu. Select the kernel to boot by moving the "shadow bar" over it with the use of the keyboard "arrow keys".
Now press this key sequence --
The system will now boot into single user mode and give you a super user shell.
Once this is done, use the below commands to setup the root password:
[idella@centos5 ~]$ sudo passwd root
[sudo] password for idella: Changing password for user root. passwd:
Authentication token manipulation error
Use the 'reboot' command to reboot the server into full operations mode.