Form fields disappearing when using HTTPS and not HTTP

[hadoob024]

Hello. I have a form field in formpage.php. A user enters in info, and then submits it. This info gets sent to formprocessor.php where I perform my error checking/sanitizing. If something is wrong, the user clicks on the 'back' button to go back and edit their fields. Now, when using HTTP, when the user clicks on the 'back' button, all their previous information is still there. However, when using HTTPS, when the user clicks on the 'back' button, all the information gets cleared. Any thoughts on why this is happening?

Incidentally, I call the following at the beggining of each of these scripts:
[code]header("Expires: Sat, 01 Jan 2000 00:00:00 GMT");
header("Last-Modified: ".gmdate("D, d M Y H:i:s")." GMT");
header("Cache-Control: post-check=0, pre-check=0",false);
session_cache_limiter("must-revalidate");[/code]