First, work through all of the steps here http://ppro.wikia.com/wiki/Troubleshooting
If your problem isn't fixed after you follow all of the steps, report back with the DETAILS asked for in the questions at the end of that link
Some folk are having somewhat similar Audio issues.
Tell us about the Audio in that source Sequence, please.
I also assume that you have let that source Audio Conform, in the source Sequence and have not done anything with the .CFA's and .PEK's (though they should be regenerated if necessary).
I am a novice to all this editing stuff, so I don't want to insult you, however I don't know where you are in all this.
I ran into this same problem when I was first trying to import files. I tried to copy them and move them from one project to another.
Then I learned how to click in the Project Box and highlight the file I wanted to bring into my current project (the right way). A simple double click from the items on the right and I was Ok.
Who knows you may be a newbe like me. If not just know all i wanted to do was help.