if its a ROM patch you're having bother with then do a power reset, if that doesn't work you may well ahve tweaked some parameters to get the first sound.
one thing I have noticed that if any knob encoder is on the edge of a change then you can unwittingly alter parameterd, the worst is the softknobs or modwheel. I suspect that the modwheel etc are the route cause of such things but please if you all have the same issue all contact access, especially if youo have a sample before and after or the chances are nobody will ever fix it.
