Fix grub boot loader

- Boot to Rescue from Linux installation CD
- Enter command: grub

# grub

grub> find /boot/grub/stage1 #OR /boot/grub/grub.conf OR /grub/grub.conf -> It show: (hdx,y) with x,y from 0 to n.
grub> root(hdx,y)
grub> setup(hdx)
grub> quit

=> done