It's a php page that first runs a mail script, then depending whether or not the email gets sent, a success page shows up to confirm it using the include() function.
I suppose if you can't disable "refresh", then what I'll have to do instead is change the confirmation page from an include to a redirect. Having said that, if the person was then to hit "back", I'd probably run into the same problem.
Having said THAT, I know that in PHP, we can detect what page was previously viewed, and if it is the success page, I can stop the script from executing.
Now, that's a lot of work, so here's my new question. Can I detect if the page has been refreshed using PHP? If so, I can insert just one or two lines of code, rather than about 50 (the confirmation page is a bit complicated).