Thanks for all of the replies. I would also be inclined to suspect the battery. She is using genuine Nikon batteries, but even so, they could still be the cause of the problem. The camera is back with Nikon so let's see if they can resolve the issue.
Also, today, Charlene acquired a second D700 camera and so she will be able to test her batteries out in the newly acquired D700. It will be interesting to see if she can duplicate the problem on the newly acquired D700. The newly acquired D700 is in immaculate condition and has only taken 1040 photographs.
If it's not battery related then let's hope that Nikon can resolve the problem fairly quickly.
I shall provide feedback as soon as possible.
'Since the mathematicians have invaded the theory of relativity, I do not understand it myself anymore' - Albert Einstein ‘I did not invent chimping, I just perfected it.' :-)