Windows – IE10 downloading files has .exe become _exe

I suggest first that you turn off all firewalls on the network and try tasklist again.

If tasklist still fails, it may be fixable even without the policy editor, by using registry editing to execute directly the same changes as would have been done by the policy editor, but this is risky and complicated.

Try using instead the free and equivalent PsList utility of Mark Russinovich.

If PsList will also fail, this will give us some additional information about the problem : Whether it is only the problem of tasklist or a general network access problem.

If nothing works, it would help to know if you can login via the network to the problematic computers by using the specified user-names and passwords.

According to this article:

PRB: Three GET Requests Are Sent When You Retrieve Plug-in Served Content

and this article:

IE Pitfalls: Document “contype” Requests

and someone else with the same problem:

"contype" user-agent making HEAD requests

IE used to make GET requests for content type but now (since IE9? for sure in IE10) has changed to HEAD request.

It is necessary to change your server process to expect a HEAD request. Both HEAD and GET requests with a user agent of contype should only return a content type and not the data

PHP example:

if($_SERVER['HTTP_USER_AGENT'] == 'contype') {
  header('Content-Type: image/svg+xml'); // or application/pdf for pdf
  die();
}