I have had two occasions when my D200 has locked up and only unlocked when the shutter was pressed again. It appears this is when the 3rd party battery has exhausted in my battery grip and the camera tries switching to the other, genuine Nikon battery. The upshot is that I thought I would put the 3rd party battery in my D80 and thus have a pair of Nikon batteries in my D200. The D80 protested and the battery level icon flashed incessantly thus in my experience I will treat 3rd party cells with caution.

Regards, Andrew