Problemas para fazer downloads de .exe

Caros amigos,

Toda a vez que alquem tenta baixa um arquivo .exe ou .rar por exemplo dá esse erro:

The requested URL could not be retrieved

While trying to retrieve the URL:

http://www.receita.fazenda.gov.br/publico/programas/IRPF/2011/PGDIRPF2011/Java/Jwindows/unico/IRPF2011win32v1.0.exe

The following error was encountered:

The request or reply is too large.

If you are making a POST or PUT request, then your request body

(the thing you are trying to upload) is too large. If you are

making a GET request, then the reply body (what you are trying

to download) is too large. These limits have been established

by the Internet Service Provider who operates this cache. Please

contact them directly if you feel this is an error.

Your cache administrator is webmaster.

Só consigo “liberar” o download quando desativo o proxy… alguém pode me ajudar?