Well...Did you suddenly move it in a new location?
These trees are known to "Shatter" for no damn reason except winds or moving it as in upseting it by moving it it will shatter.... I adore mine I collect them and everytime I move them they shatter..;'"

Good news! I figured out what was wrong with my ming!
It was in front of a mostly sunny window and was doing great, but then spring came around and I turned on my A.C. The ming had been getting a draft from a vent in the ceiling! It progressed to looking really bad.. one whole side was almost bare, with the other side still full. I moved it to another place and now it seems much happier. There is some new growth on it and it has not dropped any more leaves.
I guess the draft caused the plant to "shatter". Interesting, I had not known they do that! Thanks for the info!