I have recorded three files using the two-track mastering template. They were recorded from a digital source, using the SPDIF input of my interface. The audio is in the Pool, the files open and display the audio in the project window, but nothing comes out when I attempt to play.
I can open the Pool and try to preview the audio, no output. I can open the audio in iTunes and it plays through the interface. System sounds play through the interface.
However, none of these files give any indication of levels at the meters within Cubase or at the interface. At one time at least one of these files played properly. What could've gotten reset to cause this?

Permissions repaired, the discs check out fine. Where is my patchbay when I need it?
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Quicksilver G4, dual 1GHz, 1.5MB, OS 10.4.11
Cubase LE, Alesis io14