Frame One Of Linked SWF Executes Sometimes

I am using the loader class to load an external swf and attach it to an empty movieclip, the final step follows:
// function loadComplete(e:Event):void {
mc_launch.addChild(gLoader);
MovieClip(gLoader.content).gotoAndPlay("start");}

When navigating away from the movie clip, it's dumped as follows:
MovieClip(gLoader.content).closeAllStreams();gLoader.unload();

The linked swf has two important frames in the beginning. The first frame is labeled "hold" and has the following:
var gSC:SoundChannel = new SoundChannel();
var gSCBusy:Boolean = false;var gSlideIndex:Number = 0;
var gAudioPosition:Number = 0;
var gPlayList:Array = ["start","slide01","slide02"]
var gAudioList:Array = ["intro.mp3","",""]
var gRunMode:String = Capabilities.playerType;stop();

The fifth frame is labled "start" and the singing and dancing begins from there. The stop(); function in the first frame is used to prevent the loading swf from executing before its 100% downloaded (I had some early trouble where the music would start before the screen assets were in place). My problem: This works perfectly the first time the linked swf is downloaded and attached, however, if you navigate away and then back I get the error "gSlideIndex NAN" which indicates to me that the first frame in the linked swf is not executed on subsequent attachments, the playhead jumps straight to "start" and my globals are never declared. Why would a linked swf execute frame 1 the first time it's attached to mc_launch but not the second?