"I tried the XG .mid file in the following message and it DOES play in my RB installation so that tells me that it is something in the XG files from MidiTracks.uk which at least narrows things down a bit."

Sounds like one of my questions may have helped narrow this down .. that and SolidRock's posted file.
Wish you luck narrowing down the culprit in these downloaded files.

I do not work here, but the benefits are still awesome
Make your sound your own!