Thank you, Mac and Matt. Yes, I've check the real tracks folder, and it contains both .WAV and .WMA files.

Regarding the dominant 7 riff over a major 7 chord, here is a sample mp3 file :

http://www.mediafire.com/?mkg9fjc8gj36gbh

It's simply an 8 bars repeated chord progression - the first 8 bars is correct, and on bar 10 is where you can hear the clashing riff.

Thanks!