There's a few things you can do to get rid of this:
1) Go into Control panel, then sound and audio devices, make sure that, on the advanced setting it is set to two speakers, if you have put it to 5.1 or 7.1 by mistake, it seems to slow it down quite abit.
2) make sure that the volume level on the taskbar, and the volume on your speakers matches, - apparantly differences can also cause sound issues.