404 Error – Posts

I have two WordPress blog sites and while the one works fine, my other one isn’t. I can post fine as it shows up on the front page but once I click on the link for that post, I get a 404 error:

“The requested URL [ARTICLE_NAME] was not found on this server.”

and

“Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.”

Here is the URL and just click the headers for any one of the posts:
http://cinemanicchronicles.moviemansguide.com/

Even older posts are not working anymore…

Edit:
And I just looked and the category links are not working either.

Has anyone encountered this?

Appreciate any help. 🙂

– Brian