ATC Sound Problems

Since installing PMDG 737NG every thing works fine with the exception of the ATC voice traffic. In short, the responses to the ATC instructions are fine but 70% to 80% of the ATC instructions are not audible. It almost sounds like two audio sources fighting over CPU resources, however there aren't any other programs running when I run FS9. I have followed the FS9 suggestions(disabling some o fthe sound card features) but that results in a PMDG sound driver error on FS9 startup and FS9 promply unloads. There is also a thread that talks about turing off the Direct X accelleration I did this but still the situation has not improved. I haven't seen many threads about a similar problem.Any Help? Any Ideas?Rick [email protected]