To correct this you will need to do a database table check and then repair
- back up your database using phpMyAdmin (EXPORT)
 - choose REPAIR from the drop down menu, select all your tables and select the repair option.
 - choose OPTIMIZE from the drop down menu, select all your tables and select the optimise option
 
If you are still seeing errors after this, please open a support ticket.
ALWAYS BACKUP YOUR DATABASE FIRST
