BMW Navigator V speed alerts.

[chappers2a]

I wonder if anyone can help with this problem I have with the speed alerts and speed camera proximity warning sounds from the BMW Navigator V. When I used to creep over the speed limit the Nav V would sound a warning and at the same time lower the music from the factory fitted radio by approx 50%. I could still hear the music or news bulletin/weather etc. The same happened when approaching speed cameras. Now the Nav V cuts the music/speech etc completely and remains silent for about 10 seconds which I find a little annoying, particularly when approaching multiple speed camera sites. I contacted Garmin who suggested I do a master reset, which made no difference! Can anyone help please???