      */
     public function get verticalScrollPosition():Number 
     {
-        return (dataGroup) 
-            ? dataGroup.verticalScrollPosition 
-            : dataGroupProperties.verticalScrollPosition;
+        if (dataGroup)
+            return dataGroup.verticalScrollPosition;
+        
+        var vsp:Number = dataGroupProperties.verticalScrollPosition;
+        return isNaN(vsp) ? 0 : vsp;        
     }
 
     /**

     */
    public function get horizontalScrollPosition():Number 
    {
        return (dataGroup) 
            ? dataGroup.horizontalScrollPosition 
            : dataGroupProperties.horizontalScrollPosition;
    }

    /**


import mx.collections.IList;
import mx.core.IFactory;
import mx.core.IVisualElement;
import mx.events.PropertyChangeEvent;
import mx.utils.BitFlagUtil;

import spark.components.supportClasses.SkinnableContainerBase;
import spark.core.IViewport;
import spark.events.RendererExistenceEvent;
