Problems with POST form. Page Not Found

Hello, I have some problems sending a form via POST. When I submit the form, I get the error of 'Page Not Found'. This happens in some Internet Explorer (all are v5.5, I think). The action form is ok (<FORM action="http://www.domain.com/formprocess.html" method="post">). It happens randomly. I've the type .html associated with the php engine. And I need to use the url of action in long format (http://.....) Anybody with the same problem?? Best regards -- Antonio Mármol Albert ( toni@infurma.es ) http://www.infurma.es