As quoted from the link..

In a statement to PDN Online, Nikon USA acknowledged the D4/D800 lockup issue that I reported a month ago (several readers and other websites have reported similar issues). Nikon is currently working on a permanent solution, in the mean time you can turn off both the 'Highlights' and 'RGB Histogram' display options in order to avoid this problem:

Haven't seen any one the forums as yet with this problem? but a heads if it does start I suppose...