MyBB SQL Error

MyBB has experienced an internal SQL error and cannot continue.

SQL Error:
1194 - Table 'mybb_users' is marked as crashed and should be repaired
Query:
SELECT uid, username, birthday, birthdayprivacy, usergroup, displaygroup FROM mybb_users WHERE birthday LIKE '%-11-%' OR birthday LIKE '%-11' OR birthday LIKE '%-10-%' OR birthday LIKE '%-10' OR birthday LIKE '%-12-%' OR birthday LIKE '%-12'