Nikon tells PDN it is looking for a fix for D800 and D4 lock-up bug
Nikon has confirmed to PDN that it is investigating a problem that can cause the D800 and D4 to lock-up while shooting. The company says that the issue - identified while PDN was reviewing the camera - can be avoided by disabling Highlights and RGB Histogram on the display. At present the lock-ups require the battery to be removed to restart the camera but PDN thinks it likely that Nikon will be able to come up with a permanent fix.
The issue isn't one we've encountered while working towards our reviews of both cameras, but we'll stay in touch with Nikon and report on any updates.