You don't need to start from scratch, I found the full solution here:
So what you need to do is set the Windows partition to active, but this will mess up the boot record so you have to have a Windows 8 DVD or USB handy because when you restart it will give you an error.
You boot from the DVD/USB and then follow the instructions in that link so it fixes the boot record and then you run the update, which then works without that stupid annoying error. It keeps all the applications and settings too so no need to install from scratch.
I think this error is common on DIY desktops and people who have added SSD's because of that set Active step.