set a special page for Flash - Integrated Windows Authentication chould be also set to web.config appSettings : AjaxUploader.FlashUploadPage (RichTextEditor.AjaxUploader.FlashUploadPage for RichTextEditor)

public string FlashUploadPage { get; set; }

Public Property FlashUploadPage As String
	Get
	Set

public:
property String^ FlashUploadPage {
	String^ get ();
	void set (String^ value);
}