Long shot I know as I've tried to find an answer to this for two years. This is how my sat-nav behaves; Switch on the ignition and leave for longer than a couple of seconds between the ignition settings and the sat nav will shut off completely, by this I mean if you select the accessory position the sat nav will start but leave it for any length of time before actually switching on and dvd rom shuts down and won't restart. If you just go through the ignition switch pretty much without hesitating the dvd rom works fine and the sat nav is fine. However, if you were to switch the engine off you have to wait about five minutes before restarting if you want the sat-nav working otherwise it won't restart. I started getting the disc error message before the unit would not boot at all so I bought a second hand unit. The unit was from a 2007 so it didn't actually fit mine (different plug fittings at the back), however the laser pick-up etc was compatible so I just swapped them and since then the unit has been great except for the above. I have learned to work around it but would love to sort it. Like I said,anyone any ideas at all???