Hy sglynn!
I was in the same problem with my Ms50 and Sd1.
Did you put out the ram card and cleaned with a spray then put it back.This is very important.
If you play on gigs you need a good suport for the keybord(X-sistem) becouse some of the suport for keyboard are very nice for looking but the keybord shake to much when playing.
If you don't have try some keyboard support in X style.
This is the main reason why they freeze.