This is Matt
The only thing I can think of off-hand is to make sure you don't have the SPDIF muted.
Go to Start->Control Panel->Sounds and Audio Devices
Click on Advanced under Device volume
If the SPDIF balance is not displayed, go to Options->Properties, and put a checkmark in the box next to SPDIF in the list
Under SPDIF, make sure the volume slider is not all the way down, and that it does not show as muted.
If you can't move the slider, then SPDIF really isn't enabled, but let me know if this works.
