I was not going to share this as I thought it was an isolated incident but in the past few days I have been made aware of at least three additional incidents.
It appears to be butt rot which is explained here
http://collier.ifas.ufl.edu/CommHort...se__2___2_.pdf
There was no indication of a problem prior to the palm falling over nor was there any strong wind.
BTW, my neighbor's palm, not mine.