No crossdomain.
To be sure SlideShowPro is not the cause I perform tests with 2 simple files:
test.fla:
import com.greensock.*;
import com.greensock.loading.*;
import com.greensock.events.LoaderEvent;
import com.greensock.loading.display.*;
import com.greensock.TweenMax;
////////////////////////////////
// TwinMax Loaders //
////////////////////////////////
var mainContent:SWFLoader = new SWFLoader("sspViewerWork.swf", {name:"childMain", estimatedBytes:3000, container:container_main, x:0, y:0, alpha:1, onInit:initHandlerMain, onProgress:progressHandlerMain, onComp