[squid-users] TCP_MISS/500 only in IE, Firefox works

Hey all,

I´m having trouble with some TCP_MISS/500 in IE. A captcha image doesn´t
show in IE, only in Firefox.

Here is the log:
IE - 1348669938.883 589 10.15.14.118 *TCP_MISS/500* 8668 GET
http://pfeserv1.fazenda.sp.gov.br/sintegrapfe/imageGenerator? -
DIRECT/201.55.62.216 text/html
FF - 1348669972.713 356 10.15.14.118 *TCP_MISS/200* 7403 GET
http://pfeserv1.fazenda.sp.gov.br/sintegrapfe/imageGenerator? -
DIRECT/201.55.62.216 image/jpeg

Site link:
http://pfeserv1.fazenda.sp.gov.br/sintegrapfe/consultaSintegraServlet

Squid Cache: Version 3.1.10

The site is in a no_cache ACL:

acl sem_cache url_regex "/etc/squid/sem_cache"
cache deny sem_cache

Stop using IE is not an option.
Has anyone had this problem before? What can I do to solve this?

Thanks in advance.

-- 
Lucas Bortoluzzi (lbortoluzzi_at_portonave.com.br)
Departamento de Tecnologia da Informação
Portonave S/A - Terminais Portuários de Navegantes
Fone: 55 47 2104 3383
Fax: 55 47 2104 3303
www.portonave.com.br