Robot Disconnecting

I just updated both my cortex and controller to the 4.0v so I can use the new VEXnet Keys. The program works fine on the robot but it always disconnects when I move my lift. When I move my drive, it stays connected (4 motor drive using the joysticks), but when I move my lift which has 6 motors moving at the same time using the 6 button, it disconnects and reconnects after a five seconds. What may be wrong?

You need to give us a bit more information than this. Which programming environment? Are the batteries good and well charged? Did you upgrade the VEXnet 2.0 keys to V1.43? Which ports are the motors on? Perhaps post the code.