From: http://www.cnblogs.com/51jquery/archive/2008/11/09/1329988.html
Today, I downloaded the latest fck version and configured it according to the previous settings. However, when uploading images, an error such as this connector is disabled please check... will pop up on the browser server. Finally find a solution on the Internet
Solution:
Open Editor/filemanager/connectors/aspx/config. ascx and modify the checkauthentication () method. True is returned.
Private Bool Checkauthentication ()
{
// Warning: do not simply return "true". By doing so, you are allowing
// "Anyone" to upload and list the files in your server. You must implement
// Some kind of session validation here. Even something very simple
//
// Return (session ["isauthorized"]! = NULL & (bool) session ["isauthorized"] = true );
//
// Where session ["isauthorized"] is set to "true" as soon as
// User logs in your system.
Return True ;
}