restoring ubuntu in boot option in multi-boot set up.
 

I have installed CentOS-5 in multiboot set-up on a machine which already had win7 and ubuntu9.10 on it.When i am booting the machine i am not getting ubuntu in the boot option.I installed CentOS by selecting option-use the largest free space on current disk with default setup.
the disk partition table is below:

Device Boot Start End Blocks Id System

/dev/sda1 1 1874 15048704 27 Unknown

/dev/sda2 * 1874 1887 102400 7 HPFS/NTFS

/dev/sda3 1887 12722 87031808 7 HPFS/NTFS

/dev/sda4 12723 38914 210380360+ f W95 Ext'd (LBA)

/dev/sda5 15417 15807 3140707+ 82 Linux swap / Solaris
/dev/sda6 27557 28470 7341673+ 83 Linux

/dev/sda7 28471 38914 83884032 7 HPFS/NTFS

/dev/sda8 12723 15416 21639523+ 83 Linux

/dev/sda9 15808 17052 10000431 83 Linux

/dev/sda10 17053 17065 104391 83 Linux

/dev/sda11 17066 27556 84268926 8e Linux LVM


please help me to restore ubuntu as a boot option.

Thanks in advance!

What is the output of
on CentOS System.

it lists
other
chainloader+

apart from CentOS option

Need to add a seperate entry for Ubuntu OS therein.

when i try to edit the relevant config file i get following issue

I tried making some changes to /boot/grub/menu.lst file by logging in thru su but it throws following error:





[root@localhost avi]# /boot/grub/menu/lst | gedit

(gedit:4874): GnomeUI-WARNING **:

While connecting to session manager:
Authentication Rejected, reason : None of the

authentication protocols specified are supported and host-based authentication

failed.
bash: /boot/grub/menu/lst: No such file or directory

help me with the reason and solution.