I'm having an issue with a WordPress site that I'm in the process of developing. I've built a number of WordPress sites before, and never encountered this.
For some reason the navigation links are being a bit temperamental, and most of the time clicking on one of them leads me to a 404 page. These pages are definitely published, and the navigation is being pulled dynamically from WordPress (instead of me creating an unordered list in my header file). I did a bit of Googleing found that others had experienced a similar issue, and the recommendation was to reset the permalink settings. Whilst that has seemed to work for most people, it works for me briefly and then appears to revert back to the error the next time I go to work on the site.