That is odd. You might check your soundsettings in the control panel. The default position for all audio faders is the mid range. Could be that they are turned up on your console.
i will check this, but no... all at mid... had this more than one time but can't tell when it is happening i will try to record it for you next time sounds strange like a living processor...
Have you tried to send audio through the speakers to confirm they are working. Also are you positive the sound is from the speakers? Could it be a drive or CD spinning?
I have had issues in the past when I had other electronics in the near vicinity of the console, specifically Clear-Com belt-packs and cell phones.
If you have outboard monitors with 'brick' power supplies, you might also want to make sure that these are not too close (within a few inches) of the console chassis.
i hope it will happen again in the near future, this discussion is hot... and flirring noise is something you need to hear very electronic specific kind of sound type...