Wordpress Themes - WP Forum at BFA - Category link problem

Hi everyone, I'm new to this forum and a new user of the Atahualpa theme.
A visitor to my site pointed out that my category links dont work. When looking at the URL for the links they are missing a "/" between the domain name and "category" so it looks like this: http://domainname.comcategory/anycategory It should look like this http://domainname.com/category/anycategory
On the category widget I changed from list view to drop-down view and everything works OK. Has anyone else had this problem and if so what file do I need to go to to fix it?? Any help is appreciated.