I'm getting this error on my blog page and don't know where it's coming from. Can someone please help?

I found the problem. I had a guest writor on my blog that was a male. When I changed the site to a women's site I had to remove the men so they would not show up on the members list. Since the guest writor was a member it caused the error becuase he was the author.

I went in and manually typed in his name in the authur space and it was resolved.