1. Insert the Ubuntu installation CD into your computer's CD drive.
2. Reboot the computer and choose the 'Boot from CD-Rom option.'

3. Choose the 'Try Ubuntu without any change to your computer' menu option to boot into the Live CD.
4. Click on the 'Applications' menu at the top of the screen.
5. Choose the 'Accessories' sub-menu.
6. Choose the 'Terminal' option to open a terminal window.
7. Type the command 'fdisk -l' to locate the device name for the drive you want to fix. The device name will look like '/dev/sda.'
8. Type the command 'sudo fsck -y /dev/sda' to check the filesystem and repair any errors. Replace '/dev/sda' with the device name for the disk you want to check. The '-y' option says to run the command non-interactively. Without this option, the utility will ask for confirmation before repairing any errors it encounters.
9. Repeat the command until no more errors are reported.