A quick google reveals a long run of issues over the last few years with this unit/system (used right across the Mazda range).
We let Mazda know at our 1000K service and they said that we were on the latest firmware so theres not anything they can do, but did say that Mazda are working on the new firmware to fix this and they will let us know when this is available. Again Google suggests people have been told this by dealers for the last 2 years, only to find the "new" firmware is also buggy, so not holding my breath.
Is anyone else having this issue?
Maybe DavekMoore can weigh in on this?
Anyway, always trying to be optimistic and knowing there's absolutely nothing I can do about this, I set out to work out what is causing it to crash and how to work around it.
It turns out (for me at least) that having Bluetooth music streaming from the phone while on the SatNav screen is what is causing it to crash. Drive with Bluetooth off or on radio only and it hasn't reset once. (Haven't tried Bluetooth on for Phone calls without music but will be tested)
Being the wife's car, she does not want to have to get her phone out of her bag to plug into a cable every time she gets into the car. I don't blame her, It'd take a week just to find it in her bag

So as the ND doesn't have a CD player but 2 USB ports I set about using a USB stick as our source of music. (this is where it gets cool)
Turns out the Mazda unit has a GraceNote database loaded onto it so the unit recognises Albums and Artists from the folders/MP3's dragged onto the USB stick. So I set about dragging the "Artist" folders from the iTunes folder onto the stick.
The only problem I have is now is I don't have the playlists I normally have on the phone. I could just create a folder on the stick and drag the playlist songs from iTunes into that folder, but the Root directory on the Mazda is the usual root directory hierarchy so the playlist folder is dumped in with all the Artist folders etc so is hard to navigate and find on the run.
So what I did was, in iTunes I selected all the songs in the playlist and drag them into a folder of the same name as the playlist on the USB stick.
Opened up VLC, selected all songs in the playlist folder on the USB and dragged them into VLC.
Then, select File - Save Playlist
Call the file the same name as your playlist, select your usb stick as the save location and then select under File format - Extended M3U then save.
This creates a text doc on the USB that acts as a reference file for the Mazda unit to tell it that this is a playlist and points it to the songs location to play. Brilliant!
Now with the USB plugged in I go into USB2, give it a minute to catalogue the stick and bam, theres all your usual options of Artist - Albums - Playlists etc and they are called the proper track names from GraceNote, not what the root filename is. (IE "When I Come Around - Green Day" instead of "01-06 When i come around.m4a"
The Mazda unit is now treating/displaying the USB stick like its an iPod.
There may be other easier ways to do this but I was quite chuffed to find this out. No more Bluetooth Music streaming or plugging in a cable every time, just a tiny little USB stick plugged permanently into the unit.
Now to wait for Mazda to bring out a fix for the Bluetooth Music crash.