asked to download file when using ajax with ie. (AJAX/PHP)

Question

For some reason IE is asking us to download a file instead of running it as ajax. This works in all browsers except IE. I tried messing with the headers that it returns with no luck.

The function grabs form data then post's it the response is a can be an array of any number of items to be updated on the page.

Its not suppose to be file its suppose to be just a json response.

PHP

header('Content-type: application/json');

$error = "The Email and Password you entered could not be resolved.";
$elements[0]['target'] = '.error_report';
$elements[0]['action'] = 'inside';
$elements[0]['data'] = '<p>'.$error.'</p>';
$this->output->set_output(
  json_encode(array("elements" => $elements))
);

Javascript

$(document).ready(function () {
    jQuery.ajaxSetup({
        cache: false,
        dataType: 'json',
        error: function () {
            alert("Request was not successful. Please try again shortly.");
        }
    });

    $(document).ajaxSuccess(function (e, xhr, settings) {
        var response = xhr.responseText;
        if (settings.dataType != 'json') {
            return;
        };

        try {
            response = jQuery.parseJSON(response);
        } catch (e) {
            alert(e);
            return;
        }

        if (response.elements instanceof Array) {
            var reqs = ['target', 'action'];
            var valid = true;
            for (var i=0;i<response.elements.length;i++) {
                var cur = response.elements[i];
                var sel;

                for (var j=0;j<reqs.length;j++) {
                    if (typeof cur[reqs[j]] !== "string") {
                        valid = false;
                        break;
                    };
                };

                if (!valid) {
                    continue;
                };

                sel = $(cur.target);
                switch (cur.action) {
                    case "inside":
                        sel.html(cur.data);
                    break;
                    case "instead":
                        sel.replaceWith(cur.data);
                    break;
                    case "remove":
                        sel.remove();
                    break;
                    case "refreshPage":
                        window.location.reload();
                    default:
                        if (typeof sel[cur.action] === "function") {
                            sel[cur.action](cur.data);
                        }; // else continue
                    break;
                };
            };
        };


            // Dispatch the AJAX request, and save it to the data object so that
            // is can be referenced and cancelled if need be.

            self.data('ajaxify.xhr', jQuery.ajax({
                url: this.action,
                type: 'post',
                dataType: options.dataType,
                data: (beforeSubmitIsJquery ? beforeSubmitResult.serialize()
                                            : self.serialize()),
                success: function (/**/) {
                    cleanup();

                    options.onSuccess.apply(that, arguments);
                },
                error: function (/**/) {
                    cleanup();

                    options.onError.apply(that, arguments);
                },
                complete: function (/**/) {
                    options.onComplete.apply(that, arguments);
                }
            }));