If they are USB headphones, then yes the buttons will actually control the volume control in Windows... (Mine does anyway... I would think others would too).
There is a program that is supposed to run in the background to control this, and I have a feeling you have disabled it during the streamlining process.
Mine uses realtek drivers, and runs "rthdcpl.exe" in the background for this, but I have XP so it may be different for you.