Sometimes the database tables can crash. Also, they should be optimized from time to time. This tutorial explains how to repair and optimize database tables through phpMyAdmin.
How to Repair MySQL Database Tables?
To repair a MySQL database, first open the phpMyAdmin tool, then the Databases tab and click on the name of the desired database. Select the tables that need repair by ticking the check-boxes on the left of the table names. Then from the With Selected: drop down menu choose Repair Table. The tables will be automatically repaired and you will be presented with a page showing the results from the repair operation.