Category base problem for parent categories

Hi, I’m using WP 3.0, and when I click on the link:

http://www.mywebsite.com/movies

I get:

http://www.mywebsite.com/category/movies

My .htaccess is the default one installed by WordPress. I am using a custom structure for my permalinks: /%category%/%postname%/. ‘Movies’ is a main/parent category so /category/ shouldn’t show up in the URL (it used not to show…).

Any idea why it does that? Thanks a lot for your help!