Sorry I dont understand, do you mean this?

forum_auth_access 0 MyISAM cp1251_general_ci
forum_categories 1 MyISAM cp1251_general_ci
forum_forums 1 MyISAM cp1251_general_ci
forum_groups 40 MyISAM cp1251_general_ci
forum_posts 1 MyISAM cp1251_general_ci
forum_posts_text 0 MyISAM cp1251_general_ci
forum_prune 0 MyISAM cp1251_general_ci
forum_search_results 2 MyISAM cp1251_general_ci
forum_search_wordlist 0 MyISAM cp1251_general_ci
forum_search_wordmatch 0 MyISAM cp1251_general_ci
forum_topics 1 MyISAM cp1251_general_ci
forum_topics_watch 0 MyISAM cp1251_general_ci
forum_user_group 80 MyISAM cp1251_general_ci

yes, this.
why you use this encoding?
in all tables (not only forums) you must use utf8_general_ci

Thanks it worked. :)