Actually this traces back to the recursion issue discussed elsewhere commenting out the following lines gets rid of the problem, but then the year can no longer be changed.
Is there a way to get around this?

Date.prototype.__msh_oldSetFullYear = Date.prototype.setFullYear;
Date.prototype.setFullYear = function(y) {
var d = new Date(this);
// d.__msh_oldSetFullYear(y);
if (d.getMonth() != this.getMonth())
this.setDate(28);
// this.__msh_oldSetFullYear(y);
};