Grub Error 17: Cannot mount selected partition.

I dualboot Ubuntu and Fedora in one hard drive. Below are the scenario.

First, installed Ubuntu 10.4 on the entire disk (40GiB of size).
Then, shrink the Ubuntu installation to equal size to free up space for fedora.

Second, installed Fedora 13 using the option "Use free space on selected drives and create default layout". After the successful installation fdisk -l shows,

# fdisk -l

Disk /dev/sda: 40.0 GB, 40020664320 bytes
255 heads, 63 sectors/track, 4865 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0000b59d

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1        2330    18715693+  83  Linux
/dev/sda2            4661        4866     1648641    5  Extended
/dev/sda3            2331        2394      512000   83  Linux
/dev/sda4            2394        4661    18203648   8e  Linux LVM
/dev/sda5            4661        4866     1648640   82  Linux swap / Solaris

Partition table entries are not in disk order

Disk /dev/dm-0: 16.5 GB, 16542334976 bytes
255 heads, 63 sectors/track, 2011 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/dm-0 doesn't contain a valid partition table

Disk /dev/dm-1: 2080 MB, 2080374784 bytes
255 heads, 63 sectors/track, 252 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/dm-1 doesn't contain a valid partition table

being /dev/sda1 the Ubuntu partition and /dev/sda3 for Fedora.
Then, with Fedora grub enabled, added the Ubuntu boot parameters to /boot/grub/menu.lst.

# cat /boot/grub/menu.lst

# 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 (hd0,2)
#          kernel /vmlinuz-version ro root=/dev/mapper/vg_fcebuserv-lv_root
#          initrd /initrd-[generic-]version.img
#boot=/dev/sda
default=0
timeout=5
splashimage=(hd0,2)/grub/splash.xpm.gz
hiddenmenu
title Fedora 13 (2.6.33.3-85.fc13.i686)
        root (hd0,2)
        kernel /vmlinuz-2.6.33.3-85.fc13.i686 ro root=/dev/mapper/vg_fcebuserv-lv_root 
rd_LVM_LV=vg_fcebuserv/lv_root rd_LVM_LV=vg_fcebuserv/lv_swap rd_NO_LUKS rd_NO_MD 
rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=us rhgb quiet
        initrd /initramfs-2.6.33.3-85.fc13.i686.img
title Ubuntu 10.4, kernel 2.6.32-21-generic
        root (hd0,1)
        kernel /boot/vmlinuz-2.6.32-21-generic root=UUID=652c8b53-3751-4e86-a9fb-5e0aa5e19277 ro quiet splash
        initrd /boot/initrd.img-2.6.32-21-generic

Now, selecting Ubuntu on boot give the error, "Grub Error 17: Cannot mount selected partition".
Any advice, what needs to be done for Ubuntu to boot successfully.

Thanks.

Just a guess, but if /dev/sda3 equals (hd0,2), shouldn't /dev/sda1 equal (hd0,0), then?

I concur with House. It appears you're skipping the first partition, which is 0. The only time this would be true is if you have a factory installed "rescue" partition which you don't show in your fdisk listing.