Newbie - interface problem / question

Hi,

I havbe just started using Calibre and something has gone awry with the way that the program opens. Previously, when I started Calibre, I would see a list of the books that I had loaded. I suppose this was some kind of library view. Worked well for me.

But... something has changed, and now when I open the Calibre program, instead of seeing a list of the books that I have loaded, there is a large black screen (and a large gray screen) with one book title shown. If I click in the large black screen, it toggles through the lbooks that I have loaded, but it still only shows one at a time.

How can I restore the original view which lists all of the books that I have loaded?

Thanks