Confirm Page - Security?

The confirmation page is acting rather strangely, and I cannot trace the problem.

Here is my scenerio.

1: My confirm page simply drops the data in a database, no payment gateway at this time.
2: By the time I reach my confirm page, I have a couple of GET Variables in the URL.
3: Confirm submits to "PHP Self" which strips the GET Variables - I still need those :)
4: I replace the "PHP Self" with the appropriate "REQUEST_URI" which now retains all the GET variables. It submits to itself, but with the GET variables in tact.

HOWEVER - now the page will just land back on "confirm.php?blah=blah" but won't process the database insert(s) and won't redirect when done (likely because it doesn't finish successfully).

After looking at the code, I cannot figure out what is stopping it from processing. Is there some security added to this page, like checking for the PHP Self or something? I'm at a loss and any help would be appreciated.

EDIT 1/2 hour later - I believe the problem is in this line:

if (($_SERVER["REQUEST_METHOD"] == "POST") && (isset($_SERVER["HTTP_REFERER"]) && strpos(urldecode($_SERVER["HTTP_REFERER"]), urldecode($_SERVER["SERVER_NAME"].$_SERVER["PHP_SELF"])) > 0) && isset($_POST)) // Trigger

Since I am posting to "REQUEST URI" rather than "SELF" I have even tried to change that line to:

if (($_SERVER["REQUEST_METHOD"] == "POST") && (isset($_SERVER["HTTP_REFERER"]) && strpos(urldecode($_SERVER["HTTP_REFERER"]), urldecode($_SERVER["SERVER_NAME"].$_SERVER["REQUEST_URI"])) > 0) && isset($_POST)) // Trigger

But I still cannot get it to process!

Yes - that line of code was causing the problem. Both SELF and REQUEST_URI include the file name that is being called. I always hide the file name when it is index!

EG: If my URL was
"http://www.mysite.com/?page=confirm"

The requests were adding the file name so they looked like:
"http://www.mysite.com/index.php?page=confirm"

Since the matches were not being made - the page would not continue.
Easy fix for me. I'm not a fan or securing a page by referer in the first place, so I put my own custom check in place to act as the trigger. Works like a charm.