SQL-DATABASE ERROR

Invalid SQL: INSERT INTO sessions (userid,username,groupid,time,hash) VALUES ('0', 'Gast', '0', '1406152480', '54b71f917f51072285d0707cda83a2e9')mysql error: Table './pdsl_main1/sessions' is marked as crashed and should be repaired
mysql error number: 145
mysql version: 5.1.73
php version: 5.3.3
Date: 23.07.2014 @ 21:24
Script: /index.php
Referer: