This has happened to me twice and I'm not sure how to trouble shoot the problem.
Scenario: 1. SB800 2. D700 3. Paramount iTTL cable with hot shoe for PW. 4. Damp and dark shooting conditions as well as cool outdoors. 5. Front curtain sync with 1/60 sec minimum SS 6. Aperture preferred at f/9.0.
It will randomly drop the shutter speed to 1/25. If I turn the flash and camera off and turn the camera on followed by the flash, it shoots at 1/60.
Of course I set the aperture and shutter in manual mode and everything is OK. I suspect the cable, but I'm not sure of that. It doesn't seem to do it when the weather is warm and dry.
Scott Chapin Powder Springs, GA, USA Nikonians Team Member