Wed 17-Jul-13 12:32 AM | edited Wed 17-Jul-13 12:33 AM by MEMcD
Welcome to Nikonians!
Your camera is working as it was designed to. When the built-in Speedlight is On, when the camera is in continuous release mode only one image will be captured each time the shutter release button is pressed. See page 187 in the D700 Users Manual. The work around is to use a second Speedlight in the cameras hotshoe set in commander mode but I wouldn't count on getting 5 FPS in any flash mode other than full Manual and SU-4 mode with both Speedlights set at very low power. In TTL mode and I suspect Commander mode, the monitor pre-flash sequence between each shot will slow the FPS rate down. Using FV-Lock might allow you to use i-TTL flash control in Commander mode but you will have to give it a try.