为WebBrowser控件设置身份验证标头 - ASP.NET

I'm using WebBrowser control in my asp.net application to generate screenshots of web pages. I was able to generate images till I changed the application pool account. I've given the new application pool all the necessary rights and I'm able to browse my pages from IE. But when I navigate to it through the web browser control programatically I'm getting 401.2. I've setup "Failed request tracing rules" in my IIS 7.0 and have used Fiddler to sniff the requests and I've found that the authentication header is not right.I'm using WebBrowser control in my asp.net appl