Lee56,
Apologies for the late response to your OP 
You have said that you are trying to reinstall Windows 8.1 on your computer, can I ask why it needs to be reinstalled as in were you having problems with the present installation/or the computer in general etc.
Additionally can I ask if the computer originally had Windows 7 Home Premium as the OS and what type of Windows 8.1 disk do you have, a full retail or OEM disk, a downloaded ISO or a copy that you created yourself.
TIP
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