Alex is right, it's all about the boot. The Win 8 install App needs to see a clean boot path back to your Windows 8,0 installation or it throws it's toys out the pram. Sometimes the Win 8.0 install Repair/Automatic fix does not work. Despair not, just reload your Win 8.0 install CD and choose Repair and then the Command Prompt option. Key in the following:
c: <
cd boot <
bootrec /fixmbr <
bootrec /fixboot <
bootrec /rebuild bcd <
This cannot harm your installation and has always worked for me.
Harry
Thank you Harry and Alex,
I finally managed to install Windows 8.1.
It seems that the problem was Dual Boot all along.
I have Windows 8 and Windows 7 on the same hard drive.
To overcome the error, I copied the Windows 8 partition on to another drive using Paragon Backup and Recovery.
I then disconnected the original drive and used your 'bootrec' procedure to make sure I had the correct boot data on the Windows 8 only drive .
I booted from this drive and the Windows 8.1 installation then ran with no problems.
Hope this helps others. Good luck.