codice:
	Questo è il mio grub.conf:
#
# Sample boot menu configuration file
#
# Boot automatically after 30 secs.
timeout 30
# By default, boot the first entry.
default 0
# Fallback to the second entry.
fallback 1
# For booting GNU/Hurd
#title  GNU/Hurd
#root   (hd0,0)
#kernel /boot/gnumach.gz root=hd0s1
#module /boot/serverboot.gz
splashimage=(hd0,4)/grub/penguins.xpm.gz
# For booting GNU/Linux
title=Gentoo Linux 2.6.11-r6
root (hd0,4)
kernel /kernel-2.6.11-gentoo-r6 root=/dev/ram0 init=/linuxrc ramdisk=8192 reaoot=/dev/hda7
initrd /initrd-2.6.11-gentoo-r6
# For booting Mach (getting kernel from floppy)
#title  Utah Mach4 multiboot
#root   (hd0,2)
#pause  Insert the diskette now!!
#kernel (fd0)/boot/kernel root=hd0s3
#module (fd0)/boot/bootstrap
# For booting FreeBSD or GNU/KFreeBSD
#title  FreeBSD / GNU/KFreeBSD
#root   (hd0,2,a)
#kernel /boot/loader
# For booting NetBSD or GNU/KNetBSD
#title  NetBSD / GNU/KNetBSD
#root   (hd0,2,a)
#kernel --type=netbsd /netbsd
# For booting OpenBSD
#title  OpenBSD
#root   (hd0,2,a)
#kernel --type=netbsd /bsd
# For booting OS/2
#title OS/2
#root  (hd0,1)
#makeactive
# chainload OS/2 bootloader from the first sector
#chainloader +1
# This is similar to "chainload", but loads a specific file
#chainloader /boot/chain.os2
# For booting Windows NT or Windows95
title=Windows XP Professional
root (hd0,0)
makeactive
chainloader  +1
# For loading DOS if Windows NT is installed
# chainload /bootsect.dos
# For installing GRUB into the hard disk
#title Install GRUB into the hard disk
#root    (hd0,0)
#setup   (hd0)
# Change the colors.
#title Change the colors
#color light-green/brown blink-red/blue
 
Lo salvi in /boot/grub/grub.conf e poi dai 
Al prompt di grub fai:
	codice:
	grub> root (hd0,4)
grub> setup(hd0)
quit
 
Considera che la mia /boot è hda5 quindi devi vedere dove ce l'hai tu (se è in hda1 ad esempio metti invece di (hd0,4) (hd0,0)