Application works with fiddler ON and does not works without fiddler?

Before you start saying that this is a duplicate, I want to say right away: a topic with a similar name did not help me. When I insert the corresponding code, my program hangs and doesn't work at all. To characterize my problem, my program sends some HTTP request using HttpWebRequest and hangs at the moment of response.GetResponse(). How can I solve this? With the feedler on, everything works fine and crisp.