CGI script works in Netscape 4.7x but not 7.0 or mozilla etc.

I am trying to use a CGI script which generates a file link (i.e. a
link starting file:///<some directory or other>.  This script works as
expected with Netscape 4.77 (on Solaris) but not with Netscape 7.0 or
any Mozilla or Firefox versions.

The symptom I get with the non-working browsers is an apache 320 redirect
message instead of the link just working.  I get a page displayed which
is generated by apache saying "The page has moved to here" where 'here'
is a link to the page.  The 'here' link doesn't work either if I click
on it, but if I do "Copy link location" and paste it into the address
box on the browser then it works OK.

The CGI script is perl which I'm not very familiar with but there
doesn't seem to be anything particularly clever or complex about it.

Can anyone suggest why the later (gecko based?) browsers don't work
whereas the old 4.77 works?  I can edit the CGI if necessary but I
need some sort of clue to know what needs changing.

Is there possibly some sort of security/blocking thing going on which
prevents the more modern browsers from allowing a link to a file:///
page from being viewed when generated by CGI?

-- 
Chris Green