Experimente MonitorES . Você pode encontrar mais informações sobre este pequeno aplicativo em Lifehacker :
Tiny, portable utility MonitorES not only turns off the monitor when you lock your PC, it also pauses almost any media player and even sets your Google and Yahoo IM status to away. We've written about this utility before, but since then it has updated with support for nearly any media player, added support for Yahoo Messenger, and you can now use it to simply pause your media with the Pause key. As before, you simply need to launch the utility, set the options, and the next time you lock your workstation your monitor will turn off, and your media will pause.