Files are encrypted and stored on a WORM media device along with their encryption keys, the binary values of which are stored as a combination of written and unwritten sectors in a key storage portion of the media. The regulating means is characterized by a flat plate-shaped rotary member provided at a predetermined distance from the belt and capable of being driven to rotate by contacting with the end surface of the belt with the bias of the belt. The inner surface of the cover has at least one protrusion thereon, with the protrusion adapted to contact an inserted electrical device thereby causing the cover to cease contacting at least one portion of the frame when the electrical device is installed in the socket. Operation of the fan assembly draws air into the housing chamber through the at least one inlet opening and forces air out of the housing chamber through at least one of the primary outlet opening and the secondary outlet opening.