Every time I try to edit an existing Wiki page, it asks me to create a new page.

   In order to show students how to edit a Wiki, I created one, and added double-bracketed links on the first page to create new pages. So far, so good. I intended the top page to be only a list of links to the other pages. Then I opened the first blank page from my double-bracketed link on the top page, added some text, and saved it. Even though I just saved the page, when I try to reopen it for further editing, it asks me to create a new page. Since I have no choice, I click to create the new page again. However, all of my previous edits are still there. No matter how many times I save, when I open it for more editing is asks me to create a new page. Why is it asking me to recreate the same page over and over?
   When students open the Wiki for editing, the same thing happens.

   I've been using Moodle Wikis for nearly ten years now, and this has never happened before. Does anyone have an inkling as to what is happening?