HTTPS works perfect, but HTTP fails with timeout, what could it be?

[u01...@gmail.com]

Hi, guys. I have very specific issue. I have set up the fiddler to capture and decrypt traffic. It works fine for the HTTPS, but all my common requests over http fails with Timeout.
I use C# and HttpWebRequest to perform the request.
I configure proxy settings like this

httpWRequest.Proxy = new WebProxy("192.168.0.68:8888");

If i set up the system proxy and allow HttpWebRequest use it, it gives same result for me.

When i switch off the Fiddler HttpWebRequest reacts the same for http, and https starts throwing timeout as well.
So i suppose it just can't connect to fiddler in http mode.
Also nothing is captured when i try the HTTP, no errors, even no request attempt.
For HTTPS it works perfect.

I understand that not Fiddler probably causing the issue, but i'm stuck, maybe some one else had the same situation.

I use two pc's. Both are under Win 7 x64. One runs Fiddler. The other runs my app. They are in same network.
I use 4.4.5.1 version. About box - http://clip2net.com/s/5PGaT0
Fire wall is disabled on the pc with Fiddler.
Main cert is installed on the pc with my app.
I use the plugin for ios\android SSL cert generation.

It works ok for both HTTP and HTTPS in all browsers on both pcs.

Thanks for any help or suggestions.

P.S. I don't know if did it correct but from first try the question did not appear, so that is the copy.

[EricLaw]

If I had to guess, my first guess would be that you failed to call .Close on the object you got back from .GetResponseStream(). See http://fiddler2.com/blog/blog/2013/02/28/help!-running-fiddler-fixes-my-app-