everytime scandisk when computer start

when i on the computer it's going into scandisk i thought may be because of bad shutdown so it scandisks , then i scandisk into windows to check any erro on drive then again i off and on the computer it goes into scandisk so i in doubt what's going on something missing in system or else any one help what's problem when i start computer it always scandisk any idea...........
thanx.......
now it's starting war....................