I am having the same problem on a 2000 Diesel Espace.
I am an electronic engineer and have tracked the problem to a loss of data communication between the car and the dash. When it is OK I can see good syncronised data on the CAN bus on the blue connector to the dash. When it is faulty the data is just random continuous bits. I have taken measurements at various points on the dash PCB and am now trying to get it to go faulty to see if there is any difference. I suspect that the problem is caused by electrical noise interfering with the circuit, possibly caused by capacitors ageing. I will replace the two large ones and see if that cures it. It does not seem to be a power issue as most of the board seems to have power on it OK and although the central locking does not work, the receiver unit (square shiny box on the left) has power to it and I can see (using an oscilloscope) the signals from the plip coming out of it. Nobody else seems to have mentioned the loss of central locking. I will put more here 'when I know the answer'!!
Peter Best
April 2009