Facebook is purely web based, running on webservers and requires no local inslallation.
Ah

That's interesting.
Well, when the old drive is ready - and stable enough - to be the temporary main drive for a while, I'll try that specific Facebook link on the new drive before stripping it.
On the other hand, I might quit while I'm ahead.
BTW, on the original fault, there was a very short scroll bar on the side of the Hello Screen. One time, I stretched it to the bottom and went out via Exit. Re-booted, and lo! it was normal on the first start of FF. My joy was short-lived. Second start and it was squidged up to the top again.
So far, the fresh download and install has been normal.
It's almost as though Facebook primed something so that CCleaner reached out to the drive that was lying fallow, and corrupted one of its logical drives. Various attempts to see past the corruption, produced only the report that the total area, 50 gigs, was full. Two gigs of programs would have been nearer the truth. Disk management reported the logical drive as healthy. Sounds a bit like my doctor.
It seemed to format normally.
I was hoping to have that drive ready for downloading Win 7 last night. I'm hoping that I can confine the download to C: only, leaving D: and C: as they are. Is there anything that Win 7 might do to affect the other logical drives?