AJAX caching discepancy between IE and Mozilla

There is a discrepancy between Firefox and IE (actually about 1,252,238 but who's counting?) when dealing with AJAX calls. In this particular case I was trying to upload a file and check the status via AJAX. I was using Python to return the file upload status and then making interval calls to it. After hours of troubleshooting and wondering how in the world I was getting two different results from my AJAX calls between the two browsers (seeing how PHP is server-side), I realized the problem was IE which was caching the first or second call, therefore the progress never got past 0-2%. You have to pass a random number along in the URL arguments to force IE to retrieve fresh data.