PHP页面—缓存问题

Question

(Text below updated based on some of the responses ...)

I have done some looking online and not found an answer that makes sense to me, so before someone says this has already been answered, please have patience and read the whole thing.

I have a PHP page that outputs a standard HTML form. The form works fine. The issue that comes up is the processing page ("ProcessThis.php" or whatever). If a user has used this page once, and their browser is caching pages, the next time they use it, fill out the form, and submit to "ProcessThis.php", they get a 404 error. This seems to happen if the user has bookmarked the page for the form and comes to it from the bookmark. If they use the browser's refresh button before filling out the form, that seems to clear the issue.

I am fairly sure this is a cache issue, but I am not 100% positive. What does seem to help is when the form page loads, having the person use the refresh button on their browser.

I have done some searching and all the information I can find on refresh (the PHP refresh() function, and meta tags and all that) is that this causes a loop (refresh every "n" seconds). What I need to do I think is find a way to clear the cache for this, rather than refreshing the page every "n" seconds. I am kind of at a loss on this ... my "google-fu" is failing me, perhaps and I am using the wrong search options. Hints, suggestions, etc. would be useful. Thanks.

The form itself (as a couple of people have asked for the code) is fairly complex, and I am not sure posting the whole thing is useful. It's basic HTML form tags ... the actual form tag that starts the form is this (really basic):

<FORM METHOD="POST" ACTION="ProcessCourtReportForm.php">

Answer 1

This now falls into the "never mind" category. It turns out that the people having the problem were linking to an older copy of the form (which I had forgotten to delete from the server) which was still available, but I had deleted the process page from the server, so the 404 Error was real, because the page being looked for really didn't exist. They have been instructed to modify the bookmarks in their browsers, and I removed the older php file for the form to avoid this issue in the future. D'oh.