Cannot add components to a page.

I have installed Sitefinity and the database appears to have been correctly hooked up to my db server.  When I create a page, add a component to it, and then try to edit the component, I get a null reference exception in the editor's iframe.  Here is the stacktrace:  

[ArgumentNullException: Value cannot be null.
Parameter name: source]
   System.Linq.Enumerable.Select(IEnumerable`1 source, Func`2 selector) +798
   Telerik.Sitefinity.Data.ManagerExtensions.GetSiteProviders(IManager manager, Guid siteId) +542
   Telerik.Sitefinity.Data.ManagerBase`1.GetContextProviders() +60
   Telerik.Sitefinity.Web.UI.ProvidersSelector.get_Providers() +209
   Telerik.Sitefinity.Web.UI.ProvidersSelector.OnPreRender(EventArgs e) +57
   System.Web.UI.Control.PreRenderRecursiveInternal() +155
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +4090

[ArgumentNullException: Value cannot be null.
Parameter name: source]
   System.Linq.Enumerable.Select(IEnumerable`1 source, Func`2 selector) +798
   Telerik.Sitefinity.Data.ManagerExtensions.GetSiteProviders(IManager manager, Guid siteId) +542
   Telerik.Sitefinity.Data.ManagerBase`1.GetContextProviders() +60
   Telerik.Sitefinity.Web.UI.ProvidersSelector.get_Providers() +209
   Telerik.Sitefinity.Web.UI.ProvidersSelector.OnPreRender(EventArgs e) +57
   System.Web.UI.Control.PreRenderRecursiveInternal() +155
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Control.PreRenderRecursiveInternal() +240
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +4090

Hello Bryan,

In order to be able to provide a good solution, we need to know more about your project and how to reproduce the problem.

What Sitefinity version are you running and what edition? Are you running this through IIS or through the built-in server inside the project manager? Does this error occur on one specific page or over all of them? Did this error start occurring at some specific moment or was it there since you installed Sitefinity?

As mentioned in this forum thread:
http://www.sitefinity.com/developer-network/forums/bugs-issues-/server-error-in-'-default'-application-
in most cases the problem is caused by some misconfiguration.

I would also advise you to try re-install your project and also try different hosting server - IIS / IIS Express / Cassini.

The project should run best using IIS:
http://www.sitefinity.com/documentation/documentationarticles/installation-and-administration-guide/install-sitefinity/configuring-the-iis-to-host-sitefinity-projects

Hope this information helps.

Regards,
Vassil Vassilev
Telerik