Troubleshooting Things to Check:X Things to Check:Networking Order of the Boot Process Filesystem Corruption Recovery Run-levels Rescue Mode dd if=/dev/zero of=/dev/sda bs=446 count=1 #ÆÆ»µmbr ¹âÅÌ¿ª»ú input:linux rescue grub-install /dev/sda chroot /mnt/sysimage/ grub-install /dev/sda exit