Olha ai o meu grub.conf ja tive esse problema
# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE: You have a /boot partition. This means that
# all kernel and initrd paths are relative to /boot/, eg.
# root (hd0,5)
# kernel /vmlinuz-version ro root=/dev/hda7
# initrd /initrd-version.img
#boot=/dev/hda
default=2
timeout=5
splashimage=(hd0,5)/grub/splash.xpm.gz
title Fedora Core (2.6.5-1.358smp)
root (hd0,5)
kernel /vmlinuz-2.6.5-1.358smp ro root=LABEL=/ rhgb quiet
initrd /initrd-2.6.5-1.358smp.img
title Fedora CoreR (2.6.8.1)
root (hd0,5)
kernel /vmlinuz-2.6.8.1 (deixa a sua nova compilação parecida com essa mude apenas os dados)
title Lixowindows
rootnoverify (hd0,0)
chainloader +1