Originariamente inviato da mic
ho modificato in questo modo e ora si blocca senza mangiarsi tutta la CPU.

codice:
MovieClip.prototype.funzione= function (x,y,a,sx,sy,steps) {
	this._xstep=(Number(x)-this._x)/Number(steps);
	this._ystep=(Number(y)-this._y)/Number(steps);
	this._rot=(Number(a)-this._rotation)/Number(steps);		
	this._xsca=(Number(sx)-this._xscale)/Number(steps);
	this._ysca=(Number(sy)-this._yscale)/Number(steps);
	this._steps=steps;
	this.onEnterFrame=function () {
		if (this._steps) {
			this._rotation+=this._rot;
			this._alpha+=10;
			this._x+=this._xstep;
			this._y+=this._ystep;
			this._xscale+=this._xsca;
			this._yscale+=this._ysca;
			this._steps--;
		}else {
			delete this._xstep;
			delete this._ystep;
			delete this._xsca;
			delete this._ysca;
			delete this._steps;
			delete this.onEnterFrame
		}
	}
}
grazie
infatti nn mi ero accorto di aver scritto
this.onEnterFrame=function () {}


al posto di delete this.onEnterFrame