Problem with external swf dissapearing after so long

i have a movie using this preloader which i got here from another post that uses this code on the preloader movie itself.

if(dummy ==1){
_root.text._alpha += 10;
loaded = _root.clip.getBytesLoaded();

total = _root.clip.getBytesTotal();
num = int(perc) + “%”;
perc = (loaded/total)*100;
bar._width = perc;
if(loaded == total && dummy == 1){
_root.text._alpha = 0; = 1;

Then i have on my frame action

clip._alpha = 0;
now = 0;
text.dummy = 1;

//now load the external file into the myData object

Now it works great but when you go throught the frames and let it sit for about 30 seconds with out hitting a next or previouse to load the next swf it dissapears and then after about 30 sec it reapears and keeps doing it.

Can some one please help?