Error message when using PHP with MySQL.

I’m designing this website, but when I press submit, it gives me this error message which I don’t understand:

“Your script possibly relies on a session side-effect which existed until PHP 4.2.3. Please be advised that the session extension does not consider global variables as a source of data, unless register_globals is enabled. You can disable this functionality and this warning by setting session.bug_compat_42 or session.bug_compat_warn to off, respectively.”

What the heck is going on? Everything works, and everything is entered in the database too, but it gives me this error message, and I want to get rid of it.

This is my code: http://ole.daveyyzermans.nl/foutcode.php

If someone would take the time to look trough my code, and say what’s going on, I’d be very greatful. You can also have a place on the site.

Davey.