A common example is that you forgot your password for your computer. So you start up a liveCd in the Live Cd environment. Next, you mount your actual...
Chroot lets you change your root directory for a certain instance, like in a terminal. But to unmount and remount a different physical root partition...
I think it's interesting that if failed in both installs. Maybe run a Disk Test to make sure the disk is okay. From Ubuntu live cd there should be a...