MP3s, CCAs, WaVs and other audio formats require players (WMP, Real Player WinAmp etc. ), and these files must be associated with these players to open the files, i.e. to "play" the files. Associate the files with a non-player program and the music won't play (as well as other sound files with these file formats.). You can also configure the players not to play the files, or uninstall the players. However, students can get around that fairly easily. In fact, you won't be able to effectively prevent the students from playing the music without strict "administrative policies" (e.g. like students cannot install programs - students log-on with restricted accounts, etc.) Or, go back to basics - how about 1,000 lines if caught ? (I must not play MP3s while in class....) It is better to instill discipline.