I was having no luck finding a solution for this issue, so I figured I'd blog about it for posterity (so I can find it next time when I forget what I did). I recently setup a new blog about business continuity. I set everything up like this blog and my python blog, and everything seemed to work fine. I put my intro post out without a problem.
The next time I go to post, I put my first draft in and go to preview the post. This time, I get a message telling me the site is so embarrassed this happened but the page cannot be found. While this 404 error is kinda funny, I had no idea why I was getting it. Also, I could still post without issue. It was preview only that wasn't working.
I must have played with the permalinks a hundred times including editing the .htaccess file directly. I searched on WordPress's site and constantly came across the resolution of it's your web browser. Clear your cache. Not so in my case. I tried it from several computers.
After this, I disabled all plugins, which didn't help either. I changed the theme. No go. Finally, a week after this started, I just so happened to be looking at my settings and noticed I didn't have the same URL in the site address and the WordPress address. One had http://www.playingwithdisaster.com and the other had http://playingwithdisaster.com. Unfortunately, I can't remember which was which now, but that did the trick.