i had the same issue. (with huawei 3g modem)
you can either restore the system to an earlier restore point (before an installation of network related software).
But in my case, there wasn't any satisfiable points.
So i checked the application list (on control panel > uninstall) and came across 'connectify' software which i used for wireless internet sharing.
When i uninstalled it, problem solved !!
So check for any 3rd party network related software on your computer.. & uninstall them.