Hard drive error: DRDY ERR and UNC

Recently I was getting an error while copying files, DRDY ERR followed by UNC.

The problem appears to have been due to errors on the disk (not hardware failure as I first thought!)

I would recommend getting the System Rescue Cd:

Boot using the cd and then from the terminal type:
e2fsck -f -c -v /dev/sda1

Where /dev/sda1 is the device name of the hard disk with errors

I would also recommend updating your /etc/fstab file and ensuring fsck checks are performed on your disks.