I have a computer running Ubuntu Feisty Fawn with a 160 gig hard drive. When I boot from the hard drive, it runs the operating system and the applications from the file system on the hard drive.
I just booted the same computer from the Ubuntu Feisty Fawn Live CD. The hard drive does not show and the computer file system is contained in the RAM memory. That is what is supposed to happen. It allows you to run from the Live CD without accessing or altering the hard drive or the operating system it contains.
My Ubuntu Live CD has a copy of GNOME Partition Editor under "System", "Administration". If you start up the partition program it should show you the hard drive, its size and partitions, and the file type (ext2, ext3,). But you will not bee able to run any programs that exist on the hard drive as it is not mounted or accessible. At least you will see if the hard drive is functioning and Linux can quiry it.
Try that and let me know what you find.
Roger in Hawaii