Fix "export" on some server setups

I noticed the export-functionality doesn't work at all on some server setups. That is, clicking on "Export" just seems to do a page reload, but no file is downloaded (or shown).
This happens with all browsers (tested Chrome, FF and IE7). However, it works on my local development environment (which is a WIN/Xampp installation).

It was broken on our test-server and production server, which are both Unix/ZendServer. I did spend a few hours trying to debug and find the underlying reason for the download not working.
Tried all kind off different headers, cache settings etc. I think it might be caused by some outbut buffer option.

In the end I tested a simple die()-after the file output ... and that did the trick! Works fine in all environments :).

The fixed function in pubdlcnt.module, pubdlcnt_export_form_submit()-function looks like this now:

/**
 * Implementation of hook_submit().
 */
function pubdlcnt_export_form_submit($form, &$form_state) {

  $op = $form_state['values']['op'];
  if ($op == t('Export')) {
    $export_mode = $form_state['values']['pubdlcnt_export_mode'];
    // save the export mode
    variable_set('pubdlcnt_export_mode', $export_mode);

    $file_path = file_directory_temp() . '/public_download_count_' 
            . date('Y-m-d') . '.txt';
    export_counter_file($file_path, $export_mode);
    if (!file_exists($file_path)) {
      die("Error: File $file_path does not exists.");
    }
    if (!($fp = fopen($file_path, "r"))) {
      die("Error: Can not open file $file_path for reading.");
    }
    if (($file_size = filesize($file_path)) == 0) {
      die("Error: File $file_path is empty.");
    }

    // download (open dialog and let user save a file)
    header("Content-Disposition: attachment; filename=\"" 
      . basename($file_path) . "\"");
    header("Content-Length: $file_size");
    header("Content-Type: application/octet-stream"); readfile($file_path); 
    // delete the temporary file
    unlink($file_path);
	
    // Using die() to make sure there is no other output that can screw the download
    die();
    //return;
  }

Again, the only thing I changed was adding the die() (and a comment and //return).
No patch for now, I can create one if someone wants.