Did you import from another forum application? I agree with Brogan. Check the collations in your database. You can check the collations using a program like phpmyadmin which many hosts preinstall for you. Once inside of phpmyadmin you can view the collations. All tables and fields should be utf8_general_ci: Also try rebuilding your forum info: Admin CP -> Tools -> Rebuild Caches -> Rebuild Forum Information
Run this command in phpMyAdmin for each table. ALTER TABLE name_of_table CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci; Change the red text to the name of each table in turn. Then change the collation for the database itself using the Operations tab.
If it comes to that then you can use this script to do all tables at once: http://xenforo.com/community/thread...ease-try-again-later.14832/page-2#post-196557
