Yeesha's journal shows a flat olive-green cover. More significantly, the snapshots in what I believe is the saved game book do the same thing. I can't click on them to restore a saved game, because there's nothing there, only an olive-green rectangle. I checked the ubi site for patches, and found none. What could be up?

That looks like a technical problem - perhaps with your video card. See Myst V: System Requirements and Posting Guidelines.

And if that does not help you, I would suggest you start a new thread/post in the technical forum.

Good luck.