¿Como configuro GRUB para iniciar Ubuntu?

He instalado los dos sistemas LINUX y no consigo que arranque arranque por ninguno de los grup que se instalan.
Por el gruo de ubuntu me reconoce la instalacion de mandriva pero no hay manera de que arranque siempre vuelve a la primera pantalla del grup.Pero en mandriva es que ni siquiera reconoce la entrada de ubuntu . pego los dos menu.list para ver si sirve de ayude.En ubuntu se denonina grup.cf ....

Este es el de Mandriva 2010...

timeout 10
color black/cyan yellow/cyan
gfxmenu (hd0,5)/boot/gfxmenu
default 0

title linux
kernel (hd0,5)/boot/vmlinuz BOOT_IMAGE=linux root=UUID=4343e9a6-1373-4785-9bcc-7c3763ebf00d splash=silent vga=788
initrd (hd0,5)/boot/initrd.img

title linux-nonfb
kernel (hd0,5)/boot/vmlinuz BOOT_IMAGE=linux-nonfb root=UUID=4343e9a6-1373-4785-9bcc-7c3763ebf00d
initrd (hd0,5)/boot/initrd.img

title failsafe
kernel (hd0,5)/boot/vmlinuz BOOT_IMAGE=failsafe root=UUID=4343e9a6-1373-4785-9bcc-7c3763ebf00d failsafe
initrd (hd0,5)/boot/initrd.img

title windows
root (hd0,0)
makeactive
chainloader +1

y este otro el de ubuntu 9.10..

#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by /usr/sbin/grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#

### BEGIN /etc/grub.d/00_header ###
if [ -s /boot/grub/grubenv ]; then
have_grubenv=true
load_env
fi
set default="0"
if [ ${prev_saved_entry} ]; then
saved_entry=${prev_saved_entry}
save_env saved_entry
prev_saved_entry=
save_env prev_saved_entry
fi
insmod ext2
set root=(hd0,7)
search --no-floppy --fs-uuid --set 6f50e6be-cafe-40fb-a5cc-1da35cae86cc
if loadfont /usr/share/grub/unicode.pf2 ; then
set gfxmode=640x480
insmod gfxterm
insmod vbe
if terminal_output gfxterm ; then true ; else
# For backward compatibility with versions of terminal.mod that don't
# understand terminal_output
terminal gfxterm
fi
fi
if [ ${recordfail} = 1 ]; then
set timeout=-1
else
set timeout=10
fi
### END /etc/grub.d/00_header ###

### BEGIN /etc/grub.d/05_debian_theme ###
set menu_color_normal=white/black
set menu_color_highlight=black/white
### END /etc/grub.d/05_debian_theme ###

### BEGIN /etc/grub.d/10_linux ###
menuentry "Ubuntu, Linux 2.6.31-14-generic" {
recordfail=1
if [ -n ${have_grubenv} ]; then save_env recordfail; fi
set quiet=1
insmod ext2
set root=(hd0,7)
search --no-floppy --fs-uuid --set 6f50e6be-cafe-40fb-a5cc-1da35cae86cc
linux /boot/vmlinuz-2.6.31-14-generic root=UUID=6f50e6be-cafe-40fb-a5cc-1da35cae86cc ro quiet splash
initrd /boot/initrd.img-2.6.31-14-generic
}
menuentry "Ubuntu, Linux 2.6.31-14-generic (recovery mode)" {
recordfail=1
if [ -n ${have_grubenv} ]; then save_env recordfail; fi
insmod ext2
set root=(hd0,7)
search --no-floppy --fs-uuid --set 6f50e6be-cafe-40fb-a5cc-1da35cae86cc
linux /boot/vmlinuz-2.6.31-14-generic root=UUID=6f50e6be-cafe-40fb-a5cc-1da35cae86cc ro single
initrd /boot/initrd.img-2.6.31-14-generic
}
### END /etc/grub.d/10_linux ###

### BEGIN /etc/grub.d/20_memtest86+ ###
menuentry "Memory test (memtest86+)" {
linux16 /boot/memtest86+.bin
}
menuentry "Memory test (memtest86+, serial console 115200)" {
linux16 /boot/memtest86+.bin console=ttyS0,115200n8
}
### END /etc/grub.d/20_memtest86+ ###

### BEGIN /etc/grub.d/30_os-prober ###
menuentry "Windows 7 (loader) (on /dev/sda1)" {
insmod ntfs
set root=(hd0,1)
search --no-floppy --fs-uuid --set 2780690c69b5d8ae
chainloader +1
}
menuentry "linux (on /dev/sda6)" {
insmod ext2
set root=(hd0,6)
search --no-floppy --fs-uuid --set 4343e9a6-1373-4785-9bcc-7c3763ebf00d
linux /boot/vmlinuz BOOT_IMAGE=linux root=UUID=4343e9a6-1373-4785-9bcc-7c3763ebf00d splash=silent vga=788
initrd (hd0,5)/boot/initrd.img
}
menuentry "linux-nonfb (on /dev/sda6)" {
insmod ext2
set root=(hd0,6)
search --no-floppy --fs-uuid --set 4343e9a6-1373-4785-9bcc-7c3763ebf00d
linux /boot/vmlinuz BOOT_IMAGE=linux-nonfb root=UUID=4343e9a6-1373-4785-9bcc-7c3763ebf00d
initrd (hd0,5)/boot/initrd.img
}
menuentry "failsafe (on /dev/sda6)" {
insmod ext2
set root=(hd0,6)
search --no-floppy --fs-uuid --set 4343e9a6-1373-4785-9bcc-7c3763ebf00d
linux /boot/vmlinuz BOOT_IMAGE=failsafe root=UUID=4343e9a6-1373-4785-9bcc-7c3763ebf00d failsafe
initrd (hd0,5)/boot/initrd.img
}
### END /etc/grub.d/30_os-prober ###

### BEGIN /etc/grub.d/40_custom ###
# This file provides an easy way to add custom menu entries. Simply type the
# menu entries you want to add after this comment. Be careful not to change
# the 'exec tail' line above.
### END /etc/grub.d/40_custom ###
en ubuntu cambiando estas lineas
menuentry "linux (on /dev/sda6)" {
insmod ext2
set root=(hd0,6)
search --no-floppy --fs-uuid --set 4343e9a6-1373-4785-9bcc-7c3763ebf00d
linux /boot/vmlinuz BOOT_IMAGE=linux root=UUID=4343e9a6-1373-4785-9bcc-7c3763ebf00d splash=silent vga=788
initrd (hd0,5)/boot/initrd.img
}
menuentry "linux-nonfb (on /dev/sda6)" {
insmod ext2
set root=(hd0,6)
search --no-floppy --fs-uuid --set 4343e9a6-1373-4785-9bcc-7c3763ebf00d
linux /boot/vmlinuz BOOT_IMAGE=linux-nonfb root=UUID=4343e9a6-1373-4785-9bcc-7c3763ebf00d
initrd (hd0,6)/boot/initrd.img

por estas modificadas:

menuentry "linux (on /dev/sda6)" {
insmod ext2
set root=(hd0,6)
search --no-floppy --fs-uuid --set 4343e9a6-1373-4785-9bcc-7c3763ebf00d
linux /boot/vmlinuz BOOT_IMAGE=linux root=UUID=4343e9a6-1373-4785-9bcc-7c3763ebf00d splash=silent vga=788
initrd (hd0,6)/boot/initrd.img
}
menuentry "linux-nonfb (on /dev/sda6)" {
insmod ext2
set root=(hd0,6)
search --no-floppy --fs-uuid --set 4343e9a6-1373-4785-9bcc-7c3763ebf00d
linux /boot/vmlinuz BOOT_IMAGE=linux-nonfb root=UUID=4343e9a6-1373-4785-9bcc-7c3763ebf00d
initrd (hd0,6)/boot/initrd.img
}

Si funciona por el grup de ubuntu...

Yo quisiera tener como arranque principal el de Mandriva.