When you get this message, press Esc to go to the BIOS
Change the first boot to DVD drive
Insert a Windows 8 installation DVD in the DVD drive and restart your computer.
A black screen appears with grey text "Press any key to boot from CD or DVD". Press any key.
Select the correct regional settings.
Left click "Repair your computer" in the lower left corner.
In "Choose an option" screen - select "Troubleshoot"
In "Troubleshoot" screen - left click "Advanced options" .
Left click on "Command Prompt".
Type this command and hit enter:
Bootrec /rebuildbcd (note that there should be a space before the /)
After a few seconds it will complete the command and may indicate that it didn't find a Windows installation to repair. Ignore this and type "exit"
It should now boot correctly - don't forget to reset the first boot drive to the HDD!
(But that shouldn't really matter unless you leave a bootable disc in the drive!)