browser problem from inside firewall

[jpff@codemist.co.uk]

I have just (well yesterday) changed by firewall from an aging RedHat
system to Debian.  Most things seem OK (couple of minor spamassassin
problems) but there is one MAJOR problem that I do not understand.

The simplest form is when a user inside the firewall attempts to
upload a photo to flickr.com it just hangs and eventually times out.
If the same thing is done from the firewall itself it works
instantly.  I deduce that something in Debian is being very cautious,
but I do not know what.  The iptables I have as the same as on
previous system, and it used to work.

Any suggestions as were to look?  This is a major problem as it also
affects on-line banking which is important for the company..

==John ffitch