Well, its the law of the Sod, but I think i've fixed it myself (4 once) about 5 mins after making this post..

Simple really, just add another clear interval before the code is initialised.. seems to fix it..

clearInterval(nDelayID);
stop();
var nDelayID:Number = setInterval(this, "pause", 6000);
// where 4000 is 4000 milliseconds
function pause():Void {
clearInterval(nDelayID);
play();
// or nextFrame();
}