In the last two weeks I have had the same strange problem happen twice; A single page/post will suddenly begin redirecting to a 404 page. Everything else on the site acts like the page is still there: It comes up in the site's search results, the menu bar link turns off and on when I toggle it, it is still in my dashboard, etc. But when a user navigates to the page it redirects to a 404. Disabling plug-ins doesn't seem to fix the issue, and changing the slug doesn't fix it.
The first time it happened, I thought I fixed it by completely renaming the slug, saving it, and then renaming the slug back to the original name because it started working again. However, I'm having the issue again today and the same tactic does not seem to be fixing it.
Any thoughts on why this is happening? How to stop it from happening again, and how to fix it when it does happen?