吃花生的大灰狼

One reason why it is not permitted to shut down your mobile fix disk might be that it is still open.

For instance, suppose disk F: is the mobile disk. If it is also the incumbent disk (i.e., active or current disk) or you have opened an active window in F:, you should change this status and shut it down. Then, you might succeed in closing your USB.

Sorry............... cannot type chinese characters.