IIS and Formmail.php Problem

I have had this web page working for about 3 years:
http://www.oceanside-tower.com/contact.htm

I rebuilt the SBS 2003 server this weekend, installed IIS, PHP5, and left
all of the web directories as they were before the re-build. Web site is
working fine. So, IMO the only change is the setup of IIS. When the form
is
completed (or submitted as a blank), I get the following formmail.php
generated error: "Nothing was sent by a form. (No data was sent by POST or
GET method.) There is nothing to process here" Am I correct in my guess the
web site filters, execute permissions, etc in IIS are not set properly>

Thanks in advance