I'm also curious if your speakers do this as well?
Are these USB headphones (which are a separate audio device) or plugged into the onboard Realtek?
If plugged into the Realtek, might want to clean the input jack by putting a little alcohol on the headphone plug and working it in an out a few times.
Do you have the Realtek audio manager running? If not, it's probably in the control panel area.
Do you have the small folder icon in the upper right quadrant? If so click on it, select "Disable Front Panel Jack Detection" un-check the "Enable auto popup dialog..."
If you right click over the colored jack icons there are other options.