Change your app pool to run Integrated Pipeline instead and it should work. Also make sure that the app pool is actually running as the network service user, not as the AppPoolIdentity.

I performed the steps above and now I actually get a stack trace of it not being able to load the file or assembly.  The stack trace is below.  What else could be causing it not to load this assembly?  Thanks in advance for your help.

[FileNotFoundException: Could not load file or assembly 'UrlRewritingNet.UrlRewriter' or one of its dependencies. The system cannot find the file specified.]
   System.RuntimeTypeHandle._GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark, Boolean loadTypeFromPartialName) +0
   System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark) +64
   System.RuntimeType.PrivateGetType(String typeName, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark) +58
   System.Type.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase) +65
   System.Web.Compilation.BuildManager.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase) +342
   System.Web.Configuration.ConfigUtil.GetType(String typeName, String propertyName, ConfigurationElement configElement, XmlNode node, Boolean checkAptcaBit, Boolean ignoreCase) +52

[ConfigurationErrorsException: Could not load file or assembly 'UrlRewritingNet.UrlRewriter' or one of its dependencies. The system cannot find the file specified.]
   System.Web.Configuration.ConfigUtil.GetType(String typeName, String propertyName, ConfigurationElement configElement, XmlNode node, Boolean checkAptcaBit, Boolean ignoreCase) +351
   System.Web.Configuration.Common.ModulesEntry..ctor(String name, String typeName, String propertyName, ConfigurationElement configElement) +56
   System.Web.HttpApplication.BuildIntegratedModuleCollection(List`1 moduleList) +146
   System.Web.HttpApplication.GetModuleCollection(IntPtr appContext) +1219
   System.Web.HttpApplication.RegisterEventSubscriptionsWithIIS(IntPtr appContext, HttpContext context, MethodInfo[] handlers) +97
   System.Web.HttpApplication.InitSpecial(HttpApplicationState state, MethodInfo[] handlers, IntPtr appContext, HttpContext context) +188
   System.Web.HttpApplicationFactory.GetSpecialApplicationInstance(IntPtr appContext, HttpContext context) +295
   System.Web.HttpApplicationFactory.GetPipelineApplicationInstance(IntPtr appContext, HttpContext context) +56
   System.Web.Hosting.PipelineRuntime.InitializeApplication(IntPtr appContext) +231

[HttpException (0x80004005): Could not load file or assembly 'UrlRewritingNet.UrlRewriter' or one of its dependencies. The system cannot find the file specified.]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +8897659
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +85
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +333

I was able to get it working now...when running the installer, it listed umbraco as an application under the default website.  I removed it as an application and it began to work.

Thanks for the help.

Thanks - this happened to me when I installed Umbraco and I set "umbraco" as the name of the application folder. It set urls for the CMS as /umbraco/umbraco/login.aspx etc. So when I moved everything up to the parent, I got this error.

Had to follow Tega's advice and remove it as an application in IIS for my site.

I had exactly the same thing... pulling my hair out... but removed that Application and it now works fine :)

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