did you make sure that the option under Realtek HD Options is checkmarked? it's called "Mute the rear output device when a Front Panel headphone connected". it works fine for me.
however I have a different sort of problem ... this stubborn app keeps reverting my Speaker setup to Stereo instead of 5.1 whenever I connect headphones and then disconnect them ... grgrrrrrr ...
.: R3C0NF1GUR3D :.ASUS MVE :: 3770K bench @ 5.2GHz (delidded) :: 2x4GB Mushkin 996990 @ 2400MHz CL10 @ 1.7V :: evga 670 2GB SLI @ 1280/7108 :: Mushkin Chronos 240GB SSD RAID0 (OS) :: WD RE4 2TB (storage) 2TB :: Hitachi Deskstar 5K300 2TB (backup USB3.0) :: ASUS VG248QE 24'' 144Hz monitor
My rig with pictures"We are what we repeatedly do. Excellence, then, is not an act, but a habit." - Aristotle