Problem with links

Im setting up a wordpress install for a friend at http://fringelicious.com but I am having a problem Ive never had in the 20+installs Ive done.

If you click a category under the category menu it leaves out the slash (ex. if you click Uncategorized it tried to go to the domain http://fringelicious.comcategory/uncategorized/ so it cant connect.

Whats wrong and how do I fix it?