.htm added to the extension in firefox

I have tried this with Firefox 3.5.7 and the downloaded file extension is .exe

What version of windows and Direfox are you using?

Could you try with other browsers?

@ajay What happens when you copy and paste the URL with "/test.exe" into the browser?

I just thinking that the browser may be trying to use the URL rather than the HTTP headers to decide what the download should be. If this is the case, this will be a quick fix. The (untested) patch should update the URLs that are rendered to prevent this from happening.

Drupal also rewrites the file extension on certain files, you should have had a warning if this happened:

<?php
    // in file_munge_filename() [includes/files.inc] called from file_save_upload() by FileField module.
    if ($alerts && $original != $filename) {
      drupal_set_message(t('For security reasons, your upload has been renamed to %filename.', array('%filename' => $filename)));
    }
?>

Which has these default settings / allowed extensions: jpg jpeg gif png txt html doc xls pdf ppt pps odt ods odp

e.g.

<?php
    // in file_munge_filename()
    $extensions = '';
    foreach ($user->roles as $rid => $name) {
      $extensions .= ' '. variable_get("upload_extensions_$rid",
      variable_get('upload_extensions_default', 'jpg jpeg gif png txt html doc xls pdf ppt pps odt ods odp'));
    }
?>

If you enable the core Upload module, you can enable additional extensions for each role:

www.example.com/admin/settings/uploads ( admin > site config > file uploads )

This should be a global Drupal file setting and not part of the Upload module, but that's another story....

If you look in the directory, the physical file will be something like "example.exe.txt" if this is the case.

I believe this is no longer relevant in 2.x branch so closing; re-open if want to fix it in 1.x or doesn't fix it.