Many browser have cache for load file.But some one need client to see latest data so that we must delete the cache.Then we need to solve the cache problem.
About load file,we often load xml files/swf files/images files etc.... we can use ?cache =new Date().getTime
For example:
var load:URLLoader = new URLLoader();
load.load(new URLRequest("data.xml" + "?cache=" + new Date().getTime()));
or
var load:Loader = new Loader();
load.load(new URLRequest("atf.jpg" + "?cache=" + new Date().getTime()));