I feel sorry for you. One of the badest things is to have electronical problems with any of the expensive equipments. For all the real life things, everything is ephemeral. But my electronics equipments barely never failed and worth the investment.

I worked in a photography store and I know how hard it is for communicating correctly with the technicians and everything when you are a customer. I strongly hope that there will be a happy end at your story on your blog, but for now I don't have a answer for you

"What a photographer is without electronic these days"

I twice had similar problems - at the end of a shoot it quit triggering the strobes at all - or the frame would be black.  The next day I would take a meter reading and it seemed to meter correctly, but it would not open up the aperture (underexposing everything).   It wouldn't turn off, etc. etc.  Never got an error code though.

No one could help me diagnose what the problem was - and it would come then it would go.  I think the second time I removed the battery and everything reset.

I dug into my manual and of all the idiodic things, I learned about a negative charge... my radio trigger was dead and I plugged a synch wire into the camera from the strobe.   It worked for a whole shoot, then quit on the final setup.  There is such a thing as a negative charge that can come through the synch and scrambles the computer.  I'm lucky it didn't fry it altogether.  I now have a safe synch that fits into the hotshoe as a backup. 

Mine is a D200 as well and it seems that I created my own issues.  I doubt yours is the same problem, but maybe it will help you trouble shoot.

And, man oh man, that sucks.