I've got a simple ENTER_FRAME event with a getURL in the function but it continually calls the URL's and never stops going...
I've put stop(); inside the function and outside it, yet it doesn't stop requesting the URL's. What am I missing here?
you're misunderstanding the enterframe event.
despite the name, it is NOT an event that executes once when the playhead enters the frame. it is an event that executes N times per second where N is your swf's frames-per-second.
code attached to a frame executes once each time the play head enters the frame that contains your code. that's what you want to use.