Ok, this is very strange. Recently, i noticed that every 10-15 seconds, there would be this faint, annoying duh-dum sound coming out of my speakers. (hard to describe. sounds somewhat like the sound windows makes when you unplug a USB device, but not as pronounced and much quieter).

I closed every app and ended as many processes as I could, but the sound persists.

I look at the volume mixer and sure enough, when the sound occurs, there is a little spike in the level under "System Sounds".

I haven't installed any hardware or software in the last several weeks.

This started recently - completely out of the blue. Does anyone have any insight?