IE won't post on Windows, but will on Mac

Hello, All, I've given myself two black eyes and a bloody nose on this one, and I'm sure it's a simple solution. I have a form on the php page "entry.php": <form name="zForm" action="entry.php" method="POST"> <input type="text" name="txt" value="whatever"> </form> At the top of that page, I have the PHP code: <? echo "$REQUEST_METHOD"; //other stuff... ?> With IE 5.2 on Mac, I submit this form and I see "POST" echoed at the top of the page. With IE 5.5 on Windows, I submit this form and I see "GET". How? Why? What the? I've tried playing with different encoding types and content-types, and nothing changes the results. I also tried setting my IE 5.5 security settings to lowest and enabled everything possible. No matter what I do, I can't POST the form. Can anyone tell me just what in tarnation is going on here? Many many thanks... Jed