I'm experiencing frequent 2-tone sounds, similar to musical notes like E-G and G-E, happening every few seconds. These sounds are not beeps, but tones resembling a 2-tone car horn. Every time the sound occurs, the icons in the taskbar jump around. This happens regardless of any computer activity, yet the computer functions normally otherwise. All drivers are up to date. The tones can be up-down, down-up, or repeated instances of the same double-tone. I'm baffled. Does anyone have any ideas on what could be causing this?