Depending on your camera and what file type it cerates - you could have files with Dolby Digital sound associated with them. Have you already activated the Dolby Digital decoder? If not, you can do it in the following way: click "Help" - "Activate additional functions" - "Activate Dolby Digital stereo decoder".  Then choose "Order online" - enter your email address you used to register plus your password (if you haven't registered, you can kill two birds with one stone here and enter your serial number as well to register). The activation code will be emailed to you and you can copy and paste it into the activation dialog.