 		 */
 		override protected function configureScrollBars():void
 		{
+			var ac:ICollectionView = actualCollection;
+			var ai:IViewCursor = actualIterator;
 			var rda:Boolean = runningDataEffect;
 			
 			runningDataEffect = true;
+			actualCollection = ac || collection; // avoids null pointer error
+			actualIterator = ai || iterator;
 			
 			// This is not a perfect scrolling solution.  It looks ok when there is a partial row showing at the bottom.
 			var mvsp:int = Math.max(0, collection.length - listItems.length + 1);

{
	import flash.events.Event;
	
	import mx.collections.IList;
	import mx.controls.Tree;
	import mx.core.ScrollPolicy;
	import mx.core.mx_internal;

			super.configureScrollBars();
			
			runningDataEffect = rda;
			actualCollection = ac;
			actualIterator = ai;
		}
		
		override protected function updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):void
