[David Lilly]

Hello, I was having this same problem with .wav and .mov files with audio. Upon importing the files into Premier Pro CS4, the sound would no longer play, despite the audio mixers all displaying that sound is being registered!! We tested the sound on other programs, and discovered that the speakers were not the cause of the failure.

We finally solved the issue. On a Macintosh computer we went to Adobe Premier Pro > Preferences > Audio Hardware and changed our Default Device setting to System Default. In retrospect, we realized that the issue was caused by a recently downloaded program that changed the default sound recording device to itself, which is a program that Premier Pro cannot recognize.

In a Windows machine, the same directory is most likely located at Edit > Preferences > Audio Hardware.

I hope our solution helps to solve your issue.