Why am I getting error 0x80070585 when trying to run a PHP application on IIS 7?

Question

I'm running IIS 7 on Windows 7.

I've installed PHP v5.3 through WebMatrix, set up a website for my PHP app in IIS, and enabled read/write access for 'Everyone', for the directory.

When I browse to the application, I get the following error:

HTTP Error 500.0 - Internal Server Error
<handler> scriptProcessor could not be found in <fastCGI> application configuration
Error Code  0x80070585

Here's what I tried:

• Ensured that CGI is installed (Windows Features --> Internet Information Services --> World Wide Web Services --> Application Development Features --> CGI; it was already ticked.)

• Commented out all of extensions under the '[ExtensionList]' section in 'php.ini'.

• Noticed some discussion online about editing a file called 'fcgiext.ini'. Did a file-search on my hard drive for this file; 0 results.

• Noticed this discussion, advising that whatever is in the scriptProcessor attribute of the handlers section should also be in the fastCgi section. But I already have a file called 'Web.roleconfig' in my PHP application path, which already has a fastCgi section:

  <fastCgi>
    <application fullPath="%RoleRoot%\approot\Php\php-cgi.exe" arguments="-c %RoleRoot%\approot\Php\php.ini" />
  </fastCgi>
  

Sorry if this is all a bit incoherent. I'm not a PHP expert, and I'm not sure where to begin to solve this problem.

At the least, any hints as to whether this is an IIS or PHP or FastCgi issue would be a great help.