I have gunshot sound when midi playback instead of piano or voices

So, I got this .mid file that I made with Steinberg Cubase AI 4.5.2 and I imported it into MuseScore. I worked on it all day long, and, when I exported it to a midi file again and played it back, all the 4 satb voices play in gunshots!!!!!!!
It is extremely halarious, but in the same time, I hope I don't have to redo the whole score again............ could you guys advise me how to edit this thing and have the .mid file play a piano or voice when played back with media player instead of gunshots? other .mid file that I have exported with MuseScore play just fine, but this one seems rather special..........

HELP!!!!