A few users see a blank page

[Marco Molinari]

Hi,
I recently deployed Varnish and its performance is simply incredible.
I'm having a problem, though, which made me jump back to Squid. In the
week I used Varnish I had some users mailing me that they couldn't see
the site anymore, they just saw a blank page.
It seems this affects a small percentage of the users, as I got just
about 10 emails in a week and my users are in the 10000s, and in fact
I didn't notice any problem in the stats; so I setup two servers, one
with Squid and the other with Varnish, and the affected users see the
site only through Squid.

I'm trying to understand what's happening and with the help of some
users here's what I discovered:
- every user who has problems connects from an office (completely
different places, of course)
- at least one user connects via a proxy (she has a header that says
"Via: 1.1 SRVFW1")
- Apache serves the page, which is logged with the correct size
- they can see very small pages (a test I did just printed "Thanks " +
the timestamp)

This happens both with 1.1.2 and trunk.

On standard log files I can't find anything, I couldn't even know it
was happening if those users didn't email me. I'd like to have more
data before submitting a bug report; do you have any suggestion on how
and what I could collect?

Thanks
Marco Molinari