It just occurred to me that this one is really about quite "fundamental" things and as such a good fit for this forum section too:

http://www.pgmusic.com/forums/ubbthreads.php?ubb=showflat&Number=417858

Thanks Eddie. This is an extremely useful tip that I never even thought of. For me it's a bit of an issue because I use the melody track for external midi controls. Still, hopefully, I can work around and move them over to the soloist track and put in 'secret' melodies for my backing tracks. Great sleuthing!