AS2.0: setInterval/setTimout kills class properties

I have this issue where I have a function that when it gets called via a setInterval (or setTimeout as I have tried both), it somehow makes my class vars undefined. I have traced it right before I call the timer, right after and then inside the following function that gets called. See below:



	private function onFrontTireSuccess (evt:Object):Void {
		_allowTorqueChange = false;
	}
	
	private function onRearTireSuccess (evt:Object):Void {
		allowRandomCars = true;
		_scoreboardTimer.reset();
		_allowTorqueChange = false;
		setCarTimes();
		dispatchEvent({type:ModelLocator.UPDATE_SCOREBOARD});
		trace('onNewCar ' + currentCar);
		_nextCarTimeout = setInterval(onNewCar, _nextCarDelay);
		trace('onNewCar ' + currentCar);
	}
	
	private function onNewCar ():Void {
		trace('onNewCar ' + currentCar);
		clearInterval(_nextCarTimeout);
		if (this.currentCar <= ModelLocator.CAR_TWO){
			trace('onNewCar ' + currentCar);
			currentCar++;
			dispatchEvent({type:ModelLocator.GAME_STATUS_CONTINUE});
		} else {
			trace('end of game');
		}
	}

Has anyone else had this issue?