The present invention provides a device driver and a method for controlling access to data on a computer readable medium. According to the invention, there is provided an interface for access to a device-driver stack for a media drive, a detector for detecting insertion of a computer readable medium in said media drive, and a monitor for monitoring accessing of data on said computer readable medium. A control device establishes a location of at least one demonstration zone on said computer readable medium and determines whether a data region currently being accessed is in said demonstration zone. Said control device modifies playback of data in dependence upon the outcome of said determination.