Dynamically Loading Text which will change

programming flash
1

I need to load a text file into flash. I have tried this code:

myFile = new LoadVars();
myFile.("file.txt");
myFile.onLoad = function() {
    s_mc.s_txt.html=true;
    s_mc.s_txt.htmlText = this.cnt;
}

However, there are times when a user tells PHP to change the file content and my users that are using IE will not see my updated content unless they delete their Internet Files.
Can anyone tell me which code I should use? Thanks.