Ubuntu uses a program called Grub to load the kernel into memory when you boot the computer.
Grub has to be a tiny program to fit into the size of a bootloader, so errors it reports tend to be rather terse (usually just a number or a fraction of the string "grub"). But it normally does offer errors of some sort.
In your case, it looks like you may not even be getting as far as running grub, so I'd start by checking the BIOS settings (usually obtained by pressing a key like F2 or Delete to enter setup while the BIOS logo appears).
You might also look at using a different boot loader than grub. For example, you can install the Smart Boot Manager which is included in the Ubuntu CD (see https://help.ubuntu.com/community/SmartBootManager
If all else fails, there is a kludge. Can you boot from a floppy drive? If so, you can create a boot floppy that will load the kernel from the hard disk and boot from that; this usually works around most problems. Instructions here: https://help.ubuntu.com/community/GrubHowto/BootFloppy
(instructions should work from Windows or the live CD).
Hope that helps,
—Robert J Lee