There is a very strange problem with my friend's PC. He has 4.1 Channel Audio Speakers and a HeadPhone set. Whenever I insert the HeadPhone jack to his Front Panel Audio Connector, the Speaker doesn't mute. Both Speakers and HeadPhone play Simultaneously. The Audio drivers are of C-Media with Windows XP SP2. I checked nearly everything even "Google" on the same. I also tried to check this on my PC. On my PC it only happens if Heahphone jack is inserted half the way. Give some ideas. Will very thankful if you update my knowledge.