ASP.NET module not running on production server

[MustangPriMe]

I have a ASP.NET website which uses a module to URL rewriting of page requests (including extensionless).

The website started off as a VWD website in ASP.NET 3.5, and works happily on my development and production machines.

I'm now upgrading it to a web application in ASP.NET 4, and am facing a problem. It works perfectly within VS2010's development server, as well as IIS on my Windows 7 machine. However, installing it onto our Server 2008 R2 virtual server at our ISP, the URL module fails to run, and returns a 403.14 (directory listing forbidden) error for any URL.

If I try a URL with a .aspx extension (but one that should be handled by the url rewriting module), I get a slightly different error:
500.21 Handler "PageHandlerFactory-Integrated" has a bad module "ManagedPipelineHandler" in its module list

I'm not sure if these are two different problems, or whether they're related. Does anyone have any ideas?

The relevant part of the web.config is below.

Thanks
Paul

<system.web>
  <compilation debug="true" strict="false" explicit="true" targetFramework="4.0" /> 
  <sessionState timeout="60" mode="InProc" />
  <httpRuntime executionTimeout="2400" maxRequestLength="20480" />
  <httpModules>
    <add name="UrlRewrite" type="ZI_New.UrlRewrite" />
  </httpModules>
</system.web>
....
<system.webServer>
  <validation validateIntegratedModeConfiguration="false" />
  <modules runAllManagedModulesForAllRequests="true">
    <add name="UrlRewrite" type="ZI_New.UrlRewrite" />
  </modules>
  <handlers />
</system.webServer>