If you try the live cd, it should run from ram. it shouldn't need to be mounted.
With Ubuntu live cd, an install icon is on the desktop, so you can install from the live cd.
But, it sounds like you have a hardware problem.
Try something like Testdisk or HDD regenerator. to see if there is a problem with the hard disk.
Use anti virus, backup your data, use google.
POST BACK EVEN IF THE HELP DOESN'T HELP.
A Thank You would be nice if I have helped.
UK MP's are thieving scumbags