For some unknown reason my D3 dings. It doesn't happen all the time. I could be driving and listening to an mp3 cd, radio, dvd and all of a sudden without touching the screen it starts dinging. The same noise is heard when for instance you have your navi cd in the unit and you arrive at your destination except in my case I'm not even using the navi?! What do you guys think...?
Do you have XM installed? Mine will do that if I've viewed the map then get an XM signal interruption. If you're looking at the map when it happens, you'll see a quick flash of a message saying "XM Updating"
If not, uh... no idea.
I don't have XM. But the thing is driving me nuts! Tryed to reset it and still dings for no reason. It seems to start dinging when I arrive "close" to home. Home address is registered, so i reset the unit without registering home and still dings 
On a side note: No error screen/msg pops up when it starts dinging.
**this is making me want to sing "Would you like an apple pie with that... DING fries are done"**
If you have your nav disc out of the drive while your driving, and you go outside of an area that the D3 has stored inside it's memory, the ding is to notify you that it has to zoom out the map on the nav display.
Steve310...I'm a she, not a he 
LOL, thanks for the link 
Ok, so I've tried deleting all history to see what would happen, and of course she still dings at me. I could easily turn the sound off and my problem would be solved, but why the hell would I want to do that?!
My installer can't seem to figure it out. Pioneer themselves have no clue!
Who knows, maybe I have a defective unit?!
Steve310...I'm a she, not a he
Sorry! 
I recall that you can set a sound to play when you arrive near one of your addresses. (dog barking, bird singing, ding, etc...) Did you look into this?