My harddrive keeps getting locked on me, and I don't know how to unlock it. whenever i try to save anything to the harddrive it says "cannot modify disk". i reinstalled osx, and it let me save stuff to the harddrive. but as soon as i rebooted, the drive was locked again. I am the administrator, because the computer has only one account. why would the administrator account not have the ability to modify the harddrive? So does anybody have any idea why i cant save anything to my harddrive? how can i fix this?