Solving a category permalink issue

My site is avelim.co.il. The site is on Hebrew wordpress 3.5.1, using the theme Weaver II Pro 1.3.8 The site has 139 active plugins. One of the plugins installed is WP No Category Base - WPML compatible [login to view URL] I have 1146 categories. I created a new category with the permalink - nahariya I think that there was a category in the past with this permalink that I deleted. I assigned 18 posts to the nahariya category. However, when I try to reach the category page [login to view URL] I keep getting a 404 error. When I change the permalink of the category the issue is solved. I need to be able to use the permalink nahariya for the category without a 404 error. Freelancer should work on test site and when successful on live site. Work should be done in 24 hours after being awarded the project. Freelancer should allow 7 days for testing after he finishes his work, before getting paid