Can't get categories navigation bar to work

When I click on my Navigation Menu, top line which is categories. I get this message.

Sorry, we can’t find the content you’re looking for at this URL. Please try selecting a menu item from above or to the side of this message to get where you’d like to go.

I can not figure this out. I have posts there.

Here is my site

I have tried reseting the permalinks, removing the categories, changing the permalinks, deleting the posts and re-posting them,

I could also use a tutorial on some of the features. I am hoping that developer might be able to skype with me on thursday to walk me through a few features quickly.

Please help, very frustrated.

Thanks in advance.