Tiki needs a database to work correctly. If you get an error like table crashed (or similar), perhaps you need to fix this and Tiki will work as expected.

Table 'tiki_sessions' is marked as crashed and should be repaired

Please see some instructions
http://php.about.com/od/mysqladministration/qt/repair_mysql.htm
or
http://kb.siteground.com/article/How_to_repair_a_MySQL_database.html
or
http://www.google.com/search?q=How+to+repair+a+MySQL+database

REPAIR TABLE `tiki_sessions`;

To avoid the trouble you can also install Tiki with (or convert later) your MySQL tables to InnoDB format (instead of default MyISAM).

• http://profiles.tiki.org/Debug_Mode_Enabled
• Repair Table