I Need Help :: Somethins wrong wit my Audio...?

Well this is odd…I wonder if any of ya’ll could help me out ^^

The Audio on my computer is being played back through both my computer’s internal speakers and my Headphones when they’re plugged in!!?

I’m not sure why it’s doing this, it’s never done it before…?? 0.o

It’s like the computer is not “Muting” when I plug my headphones in… : ( any ideas?