have you tried a few tests John ? on different types of audio signals (mono vs stereo)
And can you tell us a little bit about the data being bounced to tracks. is any mono, some stereo, all stereo, exc. are there synths ?
panning ?
I can not repro it here, so im trying to get as much info as possible to help you nail down what might be the issue (whether it be sonar or tracks).