Connection failed: broken pipe

We have only recently started using Squid. We have three UK Universities
acting as neighbours. Browsers sometimes get the error message:

      While trying to retrieve the URL: <url>
      The following error was encountered:
         o Connection failed
      The system returned:
         (32) Broken pipe
      This means that:
         The remote site or server may be down. Please try again soon.

However, if the user of the browser turns the use of Squid off, they can
get to the URL. And if they turn use of Squid back on, they get the error
message.

I have looked at the log files being generated by Squid, and I have a
theory that these errors arise for every occurrence of NEIGHBOR_HIT for
one of our neighbours. However, we seem to be getting UDP_HIT_OBJs from
this neighbour. What is the likely cause of this, and how can the
neighbour or I configure Squid to avoid it?

--
Barry Cornelius                      Telephone: (0191 or +44 191) 374 4717
User Services Division, IT Service,            IT Service Office: 374 2892   
Science Site, University of Durham,                          Fax: 374 3741
Durham, DH1 3LE, UK                   E-mail: Barry.Cornelius@durham.ac.uk