C# webBrowser controller and javascript errors

When I access the page with the browser (ie9), the browser is rendering ok.

When I use the webBrowser controller I have JavaScript errors.

I know I can suppress the scripts errors, but I want them to run correctly, because they affect the rendering of the page.

Why exist this ‘rendering difference’ between the browser and the webBrowser controller, and how can I solve this problem ?

Thanks.