Today, Nikon released new firmware update for Nikon D800 / D800E and Nikon D4. The firmware update version is 1.01, to fix the lockup issue of both D800 and D4.
In a statement to PDN Online, Nikon USA acknowledged the D4 / D800 lockup issue. Nikon is currently working on a permanent solution, Nikon has not said whether the permanent solution will involve a firmware update for the D4 and D800 but it seems likely. In the mean time you can turn off both the ‘Highlights’ and ‘RGB Histogram’ display options in order to avoid this problem: