if these are your actual pictures, you also have either a telematic unit or a bluetooth module. with BT module, when it is active, it will mute the radio or CD (not the Nav voice commands) in order for you to conduct voice conversation. If something is wrong, it can still mute the system without an actual telephone or active call... usually, it happens when things are wet... you said, yours are not wet...

you need to check the connections in the radio and in the DSP module..

you can remove the nav from the connection and see if this makes any difference - the menu on the screen will be different,as it will be generated by the TV module, and then remove the TV module, to see if that makes a difference...

A lot of things in the car are controlled by telegrams on the iBus, and a low battery may manifest itself in many weird ways - the car shuts down/takes off line modules that are not deemed as essential, and their "death" gives off strange signals, that are interpreted just as wierd...

did you find any posts talking about the battery replacement/testing? there should be some talking about surface charge removal... do that procedure and see your results.. if you are going for a replacement battery, go for the strongest battery you can find... I think Douglas was the OE supplier, i do not know if they are still in business and if they make other names of the same batteries...

Thanks TerminatorX5, yes these my actual pics, i just took them moments ago.
I haven't searched nor done the "surface charge removal"... but i think from what you've said, it makes complete sense.
Oh and the vehicle does have "Bluetooth"... although i wasn't aware of the actual Bluetooth radio until you pointed it out.

It seems i have a big void under the CD Changer, you can put your hand down in their, and there is nothing there, which is different to some other photos i see of the E53 X5 CD and Nav area.
There is also a strange silver box mounted on an odd 45 degree angle just below floor height (i take it this is the Bluetooth you were referring too)
When the Girlfriend gets back, i will dismantle the whole area and check for corrosion in all plugs.

Might even disconnect the battery completely for 20minutes and reconnect if that helps reset anything (i did read that in some posts here).

I will search for battery replacements now, the battery seems fine, car starts no worries, although, that small indicator on the top of the OME battery still shows "Black"... where i'd expect it to be "Green". I see in another post TerminatorX5 you've quoted that even though the vehicle starts, the battery may still be at fault.

EDIT: I found this http://www.xoutpost.com/articles/x5/...ernatives.html

And many other very scary posts of "Jump Starting".... i'm never doing that!
But as yet, have found nothing on "surface charge removal"

We have also just discovered the A/C now comes on automatically when the car is started each time, even though AUTO is not selected.

Seems although i am searching for all other possible causes, the BM54 seems to be pointed at a lot... and judging by the 15 or so BM54 repairers on ebay, its a pretty common problem.

BM54 Radio REPAIR BMW 3 5 7 X5 E53 E46 E60 becker amp | eBay

The symptoms described are about spot on.

There are also many YouTube clips on repairing these units.
If a bad connection isn't found (and as turning ignition off and on seems to get one of my speakers working again for a short time) then i might be looking down the barrel of a BM54 repair.

I am in Australia, so a UK repairer will be of little use to me, but thought the link worth posting, if those in the UK are reading.