The failure is like this:
Kernel panic - not syncing: Attempted to kill init! Pid: 1, comm: init Not tainted 2.6.32-279.5.1.el6.x86_64 #1 Call Trace:  ? panic+0xa0/0x168  ? do_exit+0x862/0x870  ? fput+0x25/x130  ? do_group_exit+0x58/0xd0  ? sys_exit_group+0x17/0x20  ? system_call_fastpath+0x16/0x1b
And I tried the following solutions:
1) SELINUX=disabled reference
2) Press TAB, and go to the end of the command line containing
vmlinuz, at the end add the word
None of the above works.
BTW, I tried modifying the boot command by pressing
TAB on splash screen and added some errors in it. The boot up process is exactly as it was, which means the error in it doesn't make a difference. So I'm afraid if the boot command doesn't work at all.
I'm new to centos. So I could have made some stupid mistakes.
P.S. I can install that live CD on a VMbox on Ubuntu. But when I use it to boot my real machine, it fails.