I'm using WP + Atahualpa 3.5.3, Not sure how to disable Google to crawl non-exist URL

I'm using WP + Atahualpa 3.5.3, Not sure how to disable Google Bot to crawl non-existent URLs.
My Permalink is: "/%category%/%postname%.html"

The URL that users see is : domain.com/category/postname.html
But the URL that Google Bot crawled and error as 404 is : domain.com/postname.html

Does anyone know how to disallow Google Bot to crawl those URL ?
I saw in the Webmaster Tool : Link From is unavailable --> not sure what we should do to see the caused of problem ?


Thanks everyone for the helps.