The usual problem - seems that there is a usabilitry problem.
1) first clear all the cache admin->clear cache->temp/cache
2) logout - login
3) check you set the category permsission in the category admin panel not in the group admin panel.
the perm tiki_p_view_categorized must be set between a group and an cetegory. In admin->group, it iks worthless to set the perm because it is not possible to attach a category there. The only way to do it is to do it in admin->category