I have Creative ZX and Logitech Z906. The columns are connected to the optical output of the sound card. The sound card software is checked "Dolby Digital Live". When the computer is not used for 20-30 minutes and then I want to play a game or play music, there is no sound. I need to go to the sound card software to move the check mark to "No Encoder" and then return it to "Dolby Digital Live".