There are times when you need to (re-)install Ubuntu on your computer and at the same time you are in situation where booting from CD-ROM is not possible.
Luckily I found a post from Deepblue Spaces: Install Ubuntu 8.04 from Hard Disk that contains step-by-step to start Ubuntu installer from the official Ubuntu ISO.
- It involves downloading the Official Ubuntu ISO from http://www.ubuntu.com/getubuntu
- Extracting /casper/vmlinuz and /casper/initrd.gz from the ISO file.
- And modifying /grub/menu.lst file to include the boot the cd image.
For more information, please refer to the original tutorial : Deepblue Spaces: Install Ubuntu from Hard Disk.
This trick is particularly handy when you are installing Ubuntu from a computer with buggy BIOS or where CD-ROM is not readily available