.ajax success / .post callback not triggering properly in IE or Opera

.ajax success / .post callback not triggering properly in IE or Opera


I'm having an issue with .ajax and .post and their callbacks. I have
the following function:
$.post("upload.php", {file:testdata}, function() {
$("#results").html("done!");
});
testdata is a 128k string that gets posted to the server, however, in
IE and in Opera, the success/callback is triggered as soon as that the
post is hit, not after it completes. In FF, this works flawlessly,
according to firebug the post takes around 2.2s to complete, and the
success/callback triggers properly once the post is done and not
before.
Any ideas? Am I missing something?
-Greg