Someone here had the same issue - http://www.flickr.com/groups/1567431@N22/discuss/72157630611985514/ - he sorted it out by resetting Bank A (not by switching to Bank D). Perhaps he'd changed something in Bank A that stopped the mirror from being locked up - and resetting the bank changed whatever it was back to normal. For instance, on the D4, the mirror lockup is greyed out if the network connection is switched on in the menus - http://support.nikonusa.com/app/answers/detail/a_id/17810/~/%22lock-mirror-up-for-cleaning%22-grayed-out.
Copyright © Nikonians 2000, 2013
All Rights Reserved
Nikonians®, NikoScope® and NikoniansAcademy™ are trademarks owned by Nikonians.org.
Nikon®, Nikonos® and Nikkor® are registered trademarks of Nikon Corporation.