Also, you can join the forums at www.themortalkombat.com. Check the technical issues section and you will see several testimonials. I have not had a single desynch since using default buttons. While using custom mapped buttons I had at least 30 desynchs.
It generally happens when you hit attach buttons at the same time. I desynched every game I played with cyber sub zero because one of my favorite combos is bp, fp, fp+bp, slide. Almost an automatic desynch every time.