Why is my clutch disengaging on my BMW SMG?

I have a 2004 BMW M3, coupe with the SMG gearbox, every time after start the car and while I'm driving it if i release the accelerator the RPM will drop all the way down to 700rpm and if I push on the accelerator slightly the RPM will go up like if I had it on neutral and if I go harder on the accelerator the clutch will reengage again, It will do it about five time and than it will work just fine. Can somebody help me to figure this out?