From time to time I get this display on my SB700 when it's in TTL mode. (It's attached to a D80). When this happens, the flash works in manual mode, but not TTL. Changing modes on the camera doesn't make this go away, but sometimes it does go back to TTL mode all by itself. Another interesting tidbit: when I push the flash mode button on the camera, the built-in flash pops up, as if it didn't know there was an external flash attached. It seems like it never happens on fresh batteries, but it doesn't happen very often, so that might just be a coincidence.
There's no information on this in the manual. Any clues as to what's happening?
#2. "RE: What does this SB700 display mean?" In response to Reply # 1
The D80 is CLS compatible (at least most of the time). I have read that there's a difference between pre-D90 CLS and D90 or later: there was some Chinese flash linked to on Strobist that was only compatible with D90 or later. I wonder if that's a factor?
It was locked down, but next time it happens I'll try wiggling it around to see if it makes a difference.
#3. "RE: What does this SB700 display mean?" In response to Reply # 2
You might try cleaning the electrical contacts. If there is a bad connection or no connection then the Speedlight assumes the camera is not a CLS camera.
The pre-D90 dSLRs do not have full control of the SB-400, but that does not mean a different CLS. The SB-600/800 still works as CLS uints on the newer dSLRs. The other change is that the SB-400/700/900/910 do not work with TTL film cameras but the SB-600/800 both support TTL film cameras. I would not consider that a different CLS.