Often, "sound problems" are caused by:
Problem with broken wires
Problems with connector plugs not being completely plugged in
Sound Card "Driver" software corruption.
Look around in your Options and Tools settings:
Settings in Interactual DVD playback "Tools" setting for number of speakers 2, 4, 6
Mono, Stereo, Dolby, 3DAudio
Vocal Options: No Vocals, Right Vocal, Left Vocal, Both Vocal, Melody
Be sure you have: Dolby Pro Logic checkmarked for "Always Enable"
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Sometimes in InterActual DVD playback program….
some options in the Options Menu may not appear or may appear "greyed out"
Make sure that your Windows Operating System has all the latest Critical Updates and Patches
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Some DVD recordings from Warner Brothers Home Video have a "compatibility" problem with "interactual"
Microsoft has made a "patch" downloadable with the regular MS updates.
Here's the MS help article about downloading updates and patches, if you need it:
http://support.microsoft.com/kb/322389/EN-US/
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Take it slow and explore each of the above recommendations.
Post back with specific questions as they arise.
Start by Playing a DVD.
Move close-up to each of your speakers, so you can hear if it is actually kicking out any sound.
If one or more Speaker does not seem to be broadcasting sound, check the wires and connectors to that/those speaker(s)
Keep us posted with your progress.
Best Regards