"Unspecified error" from javascript in my Silverlight application

I have a Silverlight application written in C# that utilizes the Bing Maps SDK. In this application I have a page with some javascript functions to expose functions within the application. The application registers the Bing MapControl in the MainPage's constructor with:

HtmlPage.RegisterScriptableObject("Page", new MapControl(this.BingMap)); 

In the javascript function, I call the methods of the application like so:

<script type="text/javascript">
    function ClearMap() {
        var control = document.getElementById('silverlightControl');
        control.Content.Page.ClearMap();
    }
</script>

However, whenever I refer to the control.Content.Page property in a javascript function, I get an "Unspecified error". Even just setting it to a variable will cause the error, for example:

var page = control.Content.Page;

Here is the strange part. I am using this silverlight application from 2 other applications. One is a windows service, and the other a winform application. The winform embeds a visible WebBrowser into its form and uses that to call the javascript functions. When using the winform, everything works fine with no errors.

The error only occurs when calling these functions from the windows service. The service instantiates a WebBrowser object just like the winform application does, and initializes everything in the same way. The only difference is that it's running as a service, and the WebBrowser is not visible nor embedded in any forms. Could that fact possibly cause this error?

I currently have the winform application, the windows service, and the silverlight application's webservice all running on my own local machine.

UPDATE

After Gnostus' comments, I figured out that the main issue I'm having is that the "Page" object is not being created because the App class never gets initialized after navigating to the webservice from the windows service-based WebBrowser. The winform app and the service both do this the exact same way:

WebBrowser.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(WebBrowser_DocumentCompleted);
WebBrowser.Navigate("http://localhost:56062/BingMapsWebServiceTestPage.aspx");
while (WebBrowser.ReadyState != WebBrowserReadyState.Complete)
    System.Windows.Forms.Application.DoEvents();

I added some code to the MainPage's constructor where it calls HtmlPage.RegisterScriptableObject("Page", new MapControl(this.BingMap)); that will log some text when it gets hit. When I run the above code in the WebBrowser of the winform application, the following occurs:

1. The DocumentCompleted event gets fired twice (once by the browser and I assume once by the silverlight control)
2. The App() is intialized and the "Page" element successfully added in the MainPage's constructor
3. The above while loop开发者_开发技巧 completes

When I do the same from the windows service, it does #1 and #3, but not #2. Step 2 only gets hit when I call a javascript function that refers to the Page object, and only after it errors.

UPDATE 2

After messing around in a new winform application, I discovered that the silverlight control will fail to load upon calling Navigate() whenever the WebBrowser or its parent form is invisible. I found that it's possible to still call my javascript functions if the parent form is hidden AFTER the silverlight application has finished loading. Does anyone know a better way to force the silverlight app to load aside from flashing up a visible form? Is it even possible to show a form from a windows service, or am I going to have to rethink this whole thing as a console application?