download dialog incompatible with IE

[loony383]

I'm using the following code

header('Content-Description: File Transfer');
header('Content-Type: application/force-download');
header('Content-Disposition: attachment; filename='.basename($download_url));
header('Content-Transfer-Encoding: binary');
header('Expires: 0');
header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
header('Pragma: public');
header('Content-Length: $get_download3[file_size]');
ob_clean();
flush();
readfile($download_url);

to send files to the user. The problem is that when someone tries to download a file with IE (using that) it doesn't send the file, instead IE just tries to download the file but gets nothing, it then opens the program relevant to the file extension and comes up with file errors. In other browsers (firefox and safari) it downloads the file correctly but while downloading it doesn't know how big the file its downloading is until the download finishes.

 

Anyone know how to fix both of these?