Back Buttons and Forms

Hi all: I'm trying to use Header() functions to prevent browsers from caching a username/password protected page (linked to a database), so that users can't simply click the Back button to return to that page. The Headers work OK in that the page isn't cached (the browser says it has 'expired'); so far so good. But the browser offers the user the opportunity to reload the page by reposting the form data that created it - which it does; so the whole routine is useless. I've tried adding Header functions to all the pages/scripts involved, to no avail. (I'm testing all this using whatever version of Netscape that ships with Red Hat 6.2). Can't find anything really relevant in the last couple of months on this list. Any ways around this? Mulga Mick