playback inconsistent sound

I have the 2.1.2 version with .exe installer when I playback a track it sounds okay for the first bar or so and starts fading in an out with a weird phasing effect…can anyone tell me how to remedy this?

Is that a track that you’ve recorded, or one that you’ve imported?
If you generate a 30 second tone (Generate menu > Tone), does that play correctly (as a constant tone)?

If it’s a recording that you have made, how did you record it, what equipment are you using, and how is it connected together?
I’m guessing that it’s a recording that you have made, and that Windows is messing with the recording level, as described here:

Another possibility is that if you have Skype running in the background while you are recording, that can mess with the recording.