"You are not currently allowed..."

Hello,

We run squid 1.1.9 and *sometimes* for some pages our users
get the following message from the neighbour squid cache:

Error

Access Denied

Sorry, you are not currently allowed to request

    http://www.inso.com/consumer/qvp/qvpcap16.htm

>From this cache. Please check with the cache administrator if you
believe this is incorrect.

Generated by squid/1.NOVM.9@cache.bme.hu

In the access logfile one can find:

862406324.961 164 mg.kfki.hu TCP_MISS/400 483 GET
http://www.inso.com/consumer/qvp/qvpcap16.htm - SIBLING_HIT/cache.bme.hu text/html

It can occur for the most common pages as well (Alta Vista)!

What's wrong here? Or at the neighbour cache?
Can I somehow force our squid not to accept the refusal and to try to
fetch the page directly from the source?

Thank you,
Jozsef Kadlecsik

--
E-mail  : kadlec@sunserv.kfki.hu, kadlec@blackhole.kfki.hu
WWW-Home: http://www.kfki.hu/~kadlec
Address : KFKI Research Institute for Particle and Nuclear Physics
          P.O.B 49 Budapest, 1525 Hungary