1. Update kernel string in grub.conf from:
kernel /boot/vmlinuz-2.6.18-238.19.1.el5 ro root=LABEL=/
kernel /boot/vmlinuz-2.6.18-238.19.1.el5 ro root=LABEL=/ console=ttyS0
7:2345:respawn:/sbin/mingetty --autologin root --noclear ttyS0
or
s0:12345:respawn:/sbin/agetty -L 9600 ttyS0 vt100
3. Reboot VM.