I have been working for days trying to install DNN locally on my PC running Windows XP.  After several failed install attempts I finally got completely through the install wizard and it told me that DNN was installed successfully.  However when I clicked on the link to go to the site, all I get is an error page.  Running under Visual Studio 2008 in debug mode, I get the following error message:

System.Web.HttpException was unhandled by user code
  ErrorCode=-2147467259
  Message="The control collection cannot be modified during DataBind, Init, Load, PreRender or Unload phases."
  Source="System.Web"
  StackTrace:
       at System.Web.UI.ControlCollection.Add(Control child)    at DotNetNuke.UI.Utilities.MSAJAX.Register(Page objPage)    at DotNetNuke.UI.Utilities.MSAJAX.RegisterClientScript(Page objPage, String Path)    at DotNetNuke.UI.Utilities.ClientAPI.RegisterClientScriptBlock(Page objPage, String key)    at DotNetNuke.UI.Utilities.ClientAPI.RegisterClientScriptBlock(Page objPage, String key, String strScript)    at DotNetNuke.UI.Utilities.ClientAPI.RegisterClientReference(Page objPage, ClientNamespaceReferences eRef)    at DotNetNuke.UI.Utilities.ClientAPI.RegisterClientReference(Page objPage, ClientNamespaceReferences eRef)    at DotNetNuke.UI.Utilities.DNNClientAPI.EnableMinMax(Control objButton, Control objContent, Int32 intModuleId, Boolean blnDefaultMin, String strMinIconLoc, String strMaxIconLoc, MinMaxPersistanceType ePersistanceType, Int32 intAnimationFrames, String strPersonalizationNamingCtr, String strPersonalizationKey)    at DotNetNuke.UI.Utilities.DNNClientAPI.EnableMinMax(Control objButton, Control objContent, Boolean blnDefaultMin, String strMinIconLoc, String strMaxIconLoc, MinMaxPersistanceType ePersistanceType, String strPersonalizationNamingCtr, String strPersonalizationKey)    at DotNetNuke.UI.ControlPanels.IconBar.Page_PreRender(Object sender, EventArgs e) in C:\Inetpub\wwwroot\DotNetNuke\Admin\ControlPanel\IconBar.ascx.vb:line 379    at System.Web.UI.Control.OnPreRender(EventArgs e)    at System.Web.UI.Control.PreRenderRecursiveInternal()    at System.Web.UI.Control.PreRenderRecursiveInternal()    at System.Web.UI.Control.PreRenderRecursiveInternal()    at System.Web.UI.Control.PreRenderRecursiveInternal()    at System.Web.UI.Control.PreRenderRecursiveInternal()    at System.Web.UI.Control.PreRenderRecursiveInternal()    at System.Web.UI.Control.PreRenderRecursiveInternal()    at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
  InnerException:

Can anyone help solve this?  I have yet to ever see the DNN site opening page and am close to giving up and buying something.

After many tries I finally got my installation of DNN to work by adding the following to the web.config file, in the <configSections> part.

    <sectionGroup name="system.web.extensions" type="System.Web.Configuration.SystemWebExtensionsSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
      <sectionGroup name="scripting" type="System.Web.Configuration.ScriptingSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
        <section name="scriptResourceHandler" type="System.Web.Configuration.ScriptingScriptResourceHandlerSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication" />
        <sectionGroup name="webServices" type="System.Web.Configuration.ScriptingWebServicesSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
          <section name="jsonSerialization" type="System.Web.Configuration.ScriptingJsonSerializationSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="Everywhere" />
          <section name="profileService" type="System.Web.Configuration.ScriptingProfileServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication" />
          <section name="authenticationService" type="System.Web.Configuration.ScriptingAuthenticationServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication" />
          <section name="roleService" type="System.Web.Configuration.ScriptingRoleServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication" />
        </sectionGroup>
      </sectionGroup>
    </sectionGroup>

I was told by Nick at DNN support that my problem was with the AJAX configuration but I was not in a position to work with him at the time.  Later,  I finally found a post somewhere else that was talking about getting SharePoint to work with AJAX and it said to add the above code.  I figured SharePoint is similar to DNN so I tried it and it worked!  I hope others are helped by this post.  I would still like someone more knowledgable than me to tell me if I did the right thing or was I just lucky.