My SB-800 was firing like yours. The problem I had was that I used a flash bar and the cord that attached to the hot shoe had spread the camera hot shoe slides apart. When I attached the flash, there was this slight rocking motion between the flash and the camera and it would cause the flash to fire everytime I moved the camera. I sent the camera to Nikon for repair. The cost was around $120 (more or less), but along with repairing the hot shoe, they completely cleaned the camera and put new rubber grips on that were coming unglued. I was very pleased with Nikons service.