Database Error

Table 'sessions' is marked as crashed and should be repaired
DELETE FROM sessions
WHERE (sessions.created_at >= '2012-06-23 06:11:07' OR sessions.data = '' OR sessions.data IS NULL)

Array
(
    [:thirty_days] => 2012-06-23 06:11:07
)
#0 /Users/lab13/Sites/laboratories/includes/class/SQL.php(222): Query->__construct(Object(SQL), 'DELETE FROM ses...', Array, false)
#1 /Users/lab13/Sites/laboratories/includes/class/SQL.php(326): SQL->query('DELETE FROM __s...', Array, false)
#2 /Users/lab13/Sites/laboratories/includes/class/Session.php(92): SQL->delete('sessions', 'created_at >= :...', Array)
#3 [internal function]: Session::gc(1440)
#4 /Users/lab13/Sites/laboratories/includes/helpers.php(30): session_start()
#5 /Users/lab13/Sites/laboratories/includes/common.php(268): session()
#6 /Users/lab13/Sites/laboratories/index.php(5): require_once('/Users/lab13/Si...')
#7 {main}