I know how it happened. BiaB, seeing the early period, it assumed that what followed was an extension, proceeded to become confused about the song it should load. In this case it may well have come across ".WAV" or other extensions. I'm only surprised that it ended up giving me anything sensible. In fact it would have been easier to track if it has crashed.

With regards to file naming, I have been using just that sscheme since the RealBand fiasco - 1_Song1, 2_Song2 and this work very well but, in this current case, the filename had invertently been injected with an additional extension because Windows extensension were hidden.

Anyway, I thank you for all your help and I've learnt a lesson. Hopefully the developers can prevent this as it quite an insidious fault. I would not be difficult.