category error on line 304

Just new to wordpress, getting this error:
category.php on line 304 – No categories
I had set up and still have 2 main categories and 4 subcategories in one of them.
Can anyone tell me what to do???
(The blog lives here: http://www.mylousyjob.com/pritchard/)
Walter—-
PS. Still loads to learn in this new to me bloggin world!