OK, I'm not absolutely sure about my advice at this stage as I am no expert but the first few lines would appear to be the list of drives.
They appear to be in the right order.
There has to be a setting elsewhere called Boot Priority or words to that effect
Internal Optical drive would be what you use for installation, assuming it handles DVD's.
(Otherwise make a bootable USB drive as mentioned in my email).
The internal hard drive must be the one that carries the now fouled-up operating system.
It must have a drive letter to be of use here.