I'm building a web site with PHP hidden from users. In May/Jun of this year I installed MSFT automatic patches on an XP box that broke two pages (out of many) with medium sized (I think they're medium) <form method="post" ...> entries. 95% of the time on IE6.x I get "The page cannot be displayed. The page you are looking for is currently unavailable." When I get the message, a refresh gives me a post only %1 of the time and about 10% of the time a refresh throws me back to the original empty form.
The basic form for these two pages is
<form id="cr_form" enctype="multipart/form-data" method="post" action="<?php echo $self;?>" onsubmit="return ValidateChangeForm()">
Using the $self action works fine on 26 other POST forms. I currently carry this warning on the two forms when the browser is msie 6, but would like to remove it.
Warning: Under some routing conditions patches installed for Internet Explorer 6.x on Windows XP Service Pack 2 in May/June 2007 cause update failures. Sometimes a refresh resolves the problem. If you experience this problem and it persists after a refresh, please contact your network administrator or try another browser, e.g. upgrade to Internet Explorer 7, Safari, FoxFire, Mozilla, etc. No known Microsoft patch for Windows XP and Internet Explorer 6 corrects this problem yet.
I recommended the other browsers in the warning, because the error never happens on any of these browsers, only on IE 6.x. It didn't even happen on IE 5.x on an old WINNT box.
I've tried many different things, e.g., creating a cgi-bin executable to handle the post, instead of $self, changing my routing tables so the tests only go over the LAN instead of out and back to out site. But nothing works. Maybe I added too much to these forms, maybe there's some header I must send, maybe it's some unknown configuration parameter required in php.ini, maybe it because of my routing. All I know is it first broke in May and got much worse in June. The access log shows the browser never even issued the POST to the server.
The form with the worst problem only has one submit button.
<input type="submit" name="save" ...>
The form with fewer problems has one or two submit buttons, depending on the state of the cr_form.
<input type="submit" name="update" ...>
<input type="submit" name="archive" ...>