Ensure you have the most up to date sound driver that can be downloaded from the acer site, also make sure that Windows has the correct speaker configuration for your setup (either 2 set (stereo), 5.1 or 7.1), if the configuration is wrong the music and video files may be trying to play out of speakers that do no not exist.
The sound settings can be found in the Control Panel in all windows' OS.
Teris, April 2010
