When messed around, you will get a message: give root password for maintenance, and require you to press ctrl+D to continue during linux boot, then freeze the boot process. Most likely, it is because it’s booting into the single user mode.
To have the linux boot without this blocking issue, open file: /boot/grub/menu.lst, and set the default option to the config with a quiet in it, the index is zero based, so in my case, here is my config file, I am setting it to take the config with this line:
kernel /boot/vmlinuz-2.6.32-5-xen-amd64 root=/dev/xvda1 ro quiet
root@debian-linux:~# cat /boot/grub/menu.lst
default 0
timeout 5
title Debian GNU/Linux, kernel 2.6.32-5-xen-amd64
root (hd0,0)
kernel /boot/vmlinuz-2.6.32-5-xen-amd64 root=/dev/xvda1 ro quiet
initrd /boot/initrd.img-2.6.32-5-xen-amd64
title Debian GNU/Linux, kernel 2.6.32-5-xen-amd64 (single-user mode)
root (hd0,0)
kernel /boot/vmlinuz-2.6.32-5-xen-amd64 root=/dev/xvda1 ro single
initrd /boot/initrd.img-2.6.32-5-xen-amd64