I don't know if this is Mac specific, but this happened to me today.
I played Gragas one game with my 'Pineapple' rune page, then played another game with Nidalee and tried to switch over to a different rune page. The attached picture was the result.
-I currently have 4 rune pages.
-Unfortunately I don't remember the order I did masteries, champ selection, and runes. :/
-If you look at the attachment, I cannot select the blank rune pages.
Edit: Relogging did fix the problem.
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