Apache Basic Auth не работает в клиентской сети

У меня проблемы с тем, чтобы позволить клиенту увидеть сайт, заблокированный с помощью простого файла паролей Apache Basic Auth.

Он работает во всех браузерах на Mac, Windows и в нашей сети. Даже у клиента все работает дома, а не в офисе.

Что здесь могло пойти не так? Какой-то прокси что-то кеширует?

ОБНОВЛЕНИЕ: Моя конфигурация, которая всегда работала в проектах либо в конфигурации .htaccess, либо в конфигурации vhost

AuthType Basic
AuthName "Customer - Project"
AuthUserFile /mnt/drbd0/www/staging.hostname.com/site/include/passwords
Require user staging.project

ОБНОВЛЕНИЕ 2: И вот соответствующая часть из error.log

[Tue Mar 12 11:15:54 2013] [error] [client ] user  not found: /
[Tue Mar 12 11:16:15 2013] [error] [client ] user  not found: /
[Tue Mar 12 11:16:39 2013] [error] [client ] user  not found: /
[Tue Mar 12 11:17:03 2013] [error] [client ] user  not found: /
[Tue Mar 12 11:30:00 2013] [error] [client ] user staging.project: authentication failure for "/": Password Mismatch
[Tue Mar 12 11:30:17 2013] [error] [client ] user staging.project: authentication failure for "/": Password Mismatch
[Tue Mar 12 11:35:25 2013] [error] [client ] user  not found: /
[Tue Mar 12 12:34:25 2013] [error] [client ] user  not found: /
[Tue Mar 12 12:34:43 2013] [error] [client ] user download not found: /
[Tue Mar 12 13:05:08 2013] [error] [client ] user download not found: /
[Tue Mar 12 13:05:44 2013] [error] [client ] user  not found: /
[Tue Mar 12 13:05:54 2013] [error] [client ] user download not found: /
[Tue Mar 12 13:06:03 2013] [error] [client ] user download not found: /
[Tue Mar 12 17:10:29 2013] [error] [client ] user  not found: /
[Wed Mar 13 08:54:21 2013] [error] [client ] user  not found: /
[Wed Mar 13 08:54:36 2013] [error] [client ] user  not found: /
[Wed Mar 13 08:54:50 2013] [error] [client ] user  not found: /
[Wed Mar 13 08:54:52 2013] [error] [client ] user  not found: /
[Wed Mar 13 08:55:06 2013] [error] [client ] user  not found: /