sdata on Web Server won't run

We have a new implementation of a SalesLogix Web 7.5.3 server.  the slxclient runs fine, but we are having problems with the sdata not running.  We have done everything according to the setup and deployment instructions, but can't figure out why.  It reads the virtual directory okay and prompts for the logon, but then we get this message in the browser:
  <?xml version="1.0" encoding="utf-8" ?>
- <diagnosis xmlns="http://schemas.sage.com/sdata/2008/1" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:atom="http://www.w3.org/2005/Atom" xmlns:sdata="http://schemas.sage.com/sdata/2008/1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:opensearch="http://a9.com/-/spec/opensearch/1.1/" xmlns:sync="http://schemas.sage.com/sdata/sync/2008/1" xmlns:sme="http://schemas.sage.com/sdata/sme/2007" xmlns:http="http://schemas.sage.com/sdata/http/2008/1">
  <sdata:severity>error</sdata:severity>
  <sdata:sdataCode>ApplicationNotFound</sdata:sdataCode>
  <sdata:applicationCode />
  <sdata:message>Unable to locate a handler to process the request 'Default.aspx'</sdata:message>
  <sdata:stackTrace />
  <sdata:payloadPath />
  </diagnosis>

All the files are there, and the default.aspx... see screenshot.  

We are at a total loss,, and under a ton of pressure from our Sales dept to get this up and going ASAP because they can't use the iSLX app for the iPhone until we do.  HELP!!!!!!!!!!!!!!!!!!