Sleep Function get's activated during (music) playback

Hi video LAN

I've been using VLC for sometime now,,,,,but I never had this problem before,,, it looks like it Happend after the mountain lion installation ,, that now when I'm playing (music) and and my energy-saving preferences kick in the computer falls a sleep ,,, it looks like VLC doesn't overwrite the sleep function anymore,, but I can work around it if I turn on the visualization,, than it doesn't happen,,,