I was troubleshooting a colleague's blog, the blog in question had a post that would throw a 404 error whenever browsed to the full name of the post. If you're familiar with Community Kit for SharePoint, the Enhanced Blog Edition, you'll know that when you open a url to a post that doesn't exist or has been deleted, it redirects you to the main page of the blog, which makes this error even more intriguing. CKS:EBE was recognizing the post, but somewhere along the line, was not able to display the post.
I tried changing the title of the blog post to no avail, as well as created other posts that I thought would end up throwing the 404 error. What I ended up doing is changing the "BlogTitleForUrl" field on the post. It went from the original title,
To this title with an update prepended to the post.
And this fixed the problem that you can see here.