Loader waiting for variable to load...(help)

1

Hey there!
I think i might need some help here.
I have this setup, where i want an MC to load an external movie. But the external .swf is to be determined in the onRelease-function in the main timeline.
something like this…

main timeline-button:


loader_btn.onRelease = function (){
     _global.some_variable = "some_swf";
          tellTarget("some_MC"){
          gotoAndStop("load");
     }
}

and then in the ‘some_MC’ on the frame called ‘load’:


stop();
this.onEnterFrame = function(){
     if (some_variable == undefined){
          null;
     }else{
          myContainer.loadMovie(some_variable+".swf");
     }
}

This cycle only has one problem…IT’S A CYCLE. 25 times a second, i’m told that ‘undefined.swf’ could not be loaded.
Is there some clever way of solving this? Some kind of a loader just quitely waiting for a function, without having to spit something out 25 times a second?
Is it a MovieClipLoader? Is it a bird? Is it a plane?

cheers!

mikz