OK... not sure why, but I don't suppose that's any of my business.
My guess is that your installation media is too old and your system BIOS is too new (meaning like UEFI) and quite possibly you have a GPT hard drive.
To overcome these issues I would suggest grabbing the correct ISO for Windows 7 from here
Link Removed
That matches your Windows 7 license / product key (version and bit architecture)
And then use Rufus from here
http://rufus.akeo.ie/
set it up like this
And point it at your freshly downloaded ISO file and use that to create a bootable USB thumb drive. You'll need one with 4 gigs of size or larger.