USB add/remove causes screen to flash black

Three times, any time I attach or remove a USB device, or select the
"safely remove usb device" applet. It flashes the screen very
deliberately, three times, slightly slower than the old triple ding
you got when doing so in XP. System is a DFI Lanparty ICFX3200, an
intel core 2 duo 6400, Saphire radeon x1950xtx, vista home premium.
Not sure what is going on, but it does not seem to effect anything
else, but I'm sure it's not right. Any Ideas?
Thanks, Greg