Update:

I felt like there was no reason in the world why opening a backup was failing. So...I did it again. It was seemingly taking forever, so I went out and had a cup of coffee. Lo and behold, when I came back, the login dialog box was there and it opened.

I have closed and opened it a dozen times since just to check. Seems to be fine now.

Odd though, that it wouldn't open even when I copied over all the files afresh. I would get an error something like a windows error "Administrative Permission Required", and then that would pop-up repeatedly.

Thanks for your help.

Pradhan