One thing ive seen with the D200 is someone had taken their camera from airconditioned room into their housing. It most likely became moist inside the housing while underwater, even inside the camera. He then let it sit for a day, and it worked fine again. Was any airconditioned room involved?
Yep, the camera has been in the aircon for a couple of days and today was the first day outside. Also noting it was the first sunny, hot day here.
What about the battery? original nikon one? Did you swap it?
Its the original Nikon. No spare never needed one ... seems silly now

BTW, It was showing full, but I charged it anyway. It has plenty of juice for AF and shutter.
Sudden onset seems to suggest some environmental issue like water/moisture.
What firmware do you have? Latest one? Ive had the latest firmware in all 3 of my D2x cameras and shot thousands of images with them. No problem.
I must say I've always been of the adage if its not broken when it comes to firmware & drivers ... so its got what it came with. Is there a way to reset the camera ... thinking out loud, but I assume there is an internal bettery that keeps the clock and stuff alive when the main battery is out that could be reset
Changed the lens also? Maybe some weird moisture issues on the lens mount.
No, checked the contact, seating only - but I will do that.
It shot its 10000 frame this morning .... maybe its on strike !?!!?