After many attempts to install Windows 8 on my high-end desktop, and after following all of the advice given in these threads, I have concluded that Windows 8 is simply not going to install on this machine. Behind that simple statement is significant amount of fury at Microsoft for having released a woefully defective product for which there are inadequate workarounds for installation failure. But that's a story for another day.
I have reverted to Windows 7 and it's working fine. The only problem is that now I have a folder named $WINDOWS.~BT on my boot drive (C:) which simply cannot be deleted. It appears to be the backup of my Windows 7 OS performed as part of the failed Windows 8 installation, but now it is a 12GB nuisance which is impeding the performance of the SSD from which my Windows 7 boots.
I have gone into Properties and changed ownership of the folder from TrustedInstaller to myself (and my account has administrator rights). Now when I attempts to delete the folder, it grinds through the preparation process and then demands permission from my account -- the one that is already logged in -- to perform the deletion.
How do I rid myself of this huge and useless folder?