Grub Error 15 File Not Found

Recently, I updated my Ubuntu 8.04LTS with Ubuntu 10.04 LTS. After completing the full installation and reboot, grub started giving me error

"Error 15 File Not Found
Press any key to continue..."

After searching through a lot of forums I came to know that, this happens if either the file is missing or the hard drive is changed.
http://ubuntuforums.org/showthread.php?t=644773
http://forums.techarena.in/operating-systems/1144094.htm

But, this was NOT the case here. The problem was that I have two Linux installed on my system
1. Suse
2. Ubuntu

Now, the upgrade process did changed the /boot/grub/menu.lst file, but of incorrect grub. It updated the Ubuntu's where as the grub I was using of Suse.

After some juggling and fight I came to know this.
1. Booted the system in Suse.
2. mounted the ubuntu drive in Suse. mount /dev/sda3 /mnt
3. Open /mnt/boot/grub/menu.lst
4. Copy the new listings from ubuntu's menu.lst
5. Open the Suse's /boot/grub/menu.lst
6. Paste the copied listings here.
7. Save the file
8. Reboot.

There you go. You can see the list of Ubuntu 10.04 installed.