It sound like you've got a ringing bell sound assigned to a Windows "end-of-event" or "program-close" event in the Control-panel->sounds control. During renders, Poser does a number of sub-routines, which windows CAN interpret as separate programs or sub-routines starting & stopping (each an event to be announced by whatever sound is assigned). It's different in different versions of Windows. I get a single one when I render, just before the render itself starts creeping up the screen. Try poking around in control Panel->sounds to see if you can find what events have that sound assigned. then you can either re-assign a new sound to that event, or no sound at all. This pic is what it looks like in XP. That's my best guess from your description - Good Luck!