If there's no DVD then it could be a failure of the drive which contains the software - this can sometimes be a compact flash card or some other storage device that has a finite number of reads and writes (or just age) before failure.

I did read that some models may rely on 3G - that signal has now been switched off.

No i havent tried the reset, thats where i hold the power button, for quite a while, no? Sometimes works, from what i hear!

Hi its been doing it since i bought the car, the seller did mention this though!

No i havent tried those!

So literally just disconnecting the 12v battery for a min?

Hi, its the widescreen unit.

Screen itself is fine, reverse cam is perfect, etc

I do recall the guy i bought it from, mention that he had the 12v battery replaced a few weeks prior, said he used his phone for navigation, but can't remember if he said only 'since' the Battery was replaced.

It will be at BMW for an airbag recall, in the next few months, but i'm sure BMW will 'find a way' to do work that isn't needed, re. the NAV

Has the HK pro logic 7 surround sound, which sounds great, the NAV is the only niggle!