I was having the same problem. This might sound silly, but make sure to go to the Control Panel and get into the Network section. Then Setup or Change your home or small office network. In there, create your network (all you really need to do is name it and click through to finish, don't bother trying to "set up" your Xbox or other computers).
I did this tonight after trying everything else with Media Connect and having no luck. After doing this, my PC recognized the 360 on the first try, and everything works perfectly.
Worth trying before you start downloading and installing/uninstalling various programs.